THERE ARE NUMEROUS chateaux in Bordeaux that produce marvelous wines but, for inexplicable reasons, nobody's ever heard of them. Two of the best-kept secrets of this mammoth wine-producing area in southeast France are the wines of Chateau Meyney in St. Estephe, and Chateau La Dominique in St. Emilion.

For most bordeaux enthusiasts, St. Emilion's wines -- so supple, round, generous and quick-maturing -- are best exemplified by the richness and majesty of Chateaux Cheval Blanc and Ausone at the top, followed by such alleged luminaries as Figeac, Pavie, Magdelaine, Bel-Air and Canon. These chateaux are the best-known superstars of the St. Emilion district, are highly touted in wine books and widely available in major wine shops. But who has ever heard of La Dominique? Talk to any knowledgeable bordeaux broker or English master of wine and the standard response is, "Great wine when I have tasted it, but unfortunately I don't see much of it these days".

There are several reasons La Dominique hasn't caught on. The chateau, although ranked as one of St. Emilion's "Grands Crus Classes" in 1955, failed to be included in the list of the top 12 "Premier Grands Crus Classes," which supposedly represents the best wines of this area. Its production is not especially large, about 6,000 cases in a good year. And no national importer has purchased enough of the wine to make it widely available across the country, thereby exposing consumers to its excellent quality.

My first exposure to La Dominique was at a dinner party in Bordeaux in 1975. The vintage served was 1955, and it eclipsed a number of more famous wines at the table, including the Cheval Blanc and Figeac. I felt that any wine that elicited such interest and showed such richness required further investigation, so I visited the chateau in 1979, and again last June.

La Dominique is located on a gravelly plain northwest of the medieval town of St. Emilion. Its vineyard is strategically sandwiched between its famous neighbor, Cheval Blanc, and the border of Pomerol, where the two top-notch Pomerol vineyards of L'Evangile and La Conseillante are situated. La Dominique's growing reputation for fruity and excellent wine was well-justified at a recent tasting sponsored by the Gordon Palmateer Company, its representative in that area. The vintages of La Dominique tasted included the 1967, 1971, 1973, 1974, 1975, 1976, 1978, 1979, 1980 and 1981, the lesser wines drawn from the barrel and flown in for the tasting.

La Dominique produces deeply colored, intensely fruity wine, generally without harsh tannins. Most observers who are familiar with the chateau's wines have felt that the quality at the property was quite variable in the 1950s and 1960s. However, in 1970 the estate was sold to the Foyat family, who took over La Dominique with great enthusiasm. Temperature-controlled, stainless steel fermentation tanks, installed in 1972, have given the winemaker more control over the wine, and renewed efforts were made to improve the quality of an already good wine. Consequently, La Dominique currently is considered one of the top St. Emilion wines, and now seems considerably undervalued vis-a -vis its more publicized neighbors. The blend of grapes used at La Dominique is said to be 50 percent merlot and 50 percent cabernet franc. The wine is given a lengthy fermentation and usually is kept two years in small oak barrels, one-third of which are new.

At the tasting, the wine quality was impressive. Surprisingly, the 1967, 1973 and 1974 were all very full of color and life, with more fruit than most wines from these mediocre vintages. The 1971 was simply extraordinary, and may well be the very best wine produced in St. Emilion in that vintage. The 1975 was particularly rich, but very tannic. The 1976 and 1978 were wonderful successes for the vintages, deep, darkly colored, yet supple and fruity. The 1979 was young and surprisingly tannic and hard for the vintage; the 1980 fruity, supple and soft, but certainly one of the most attractive wines from this year; and the 1981 muscular, fleshy, deeply colored and full of potential.

La Dominique has been made available to local retailers for delivery in mid-November. If you are not inclined to spend $40-plus for Cheval Blanc or Ausone, or have found Figeac and some of its neighbors overpriced and disappointing lately, a search for La Dominique is well worth the effort. The vintages that will be available for sale are the 1975, 1976, 1978, 1979 and, in a year, 1981. The prices for wine of such quality are realistic, ranging from a high of $16 for the hard-to-get, long-lived 1975, to $12 for the lovely 1976, 1979 and 1981.

Chateau Meyney in the Medoc commune of St. Estephe is another underrated property that consistently produces wine well above its official pedigree -- in this case, "Cru Bourgeois Exceptionnel."

St. Estephe, the most northern Medoc commune, is the home of many fine wines, most notably Chateau Cos D'Estournel and Montrose. Meyney is beautifully situated adjacent to the Gironde River, slightly north of Montrose. The property is owned and well run by the Cordier family, who have gained international fame for their two exquisite St. Julien chateaux of Gruard Larose and Talbot.

In terms of vinification and the handling of the wine, Meyney is very similar to La Dominique. The wine is fermented in stainless steel tanks, and aged in oak barrels for two years. Like La Dominique's, one-third of the barrels are new each year. The blend of grapes, however, is noticeably different, with 65 percent cabernet sauvignon and 35 percent merlot used primarily, and the balance consisting of petit verdot and cabernet franc. The wine is full-bodied, generous and tannic. It is usually fruitier and chunkier than most other St. Estephes, and is capable of aging for 10 to 20 years in a good vintage. With more than 20,000 cases produced in a decent year, the wine is widely available through its New York importer, Chateau and Estates. Meyney sells for significantly less than other wines of its quality, and can usually be found for $9 to $14, depending on the vintage. In recent years, Meyney has produced a lovely, deeply colored, fairly forward 1979; a deep, fruity, full-bodied and tannic 1978; a magnificent 1975 that is just beginning to evolve and open; a soft, fully mature 1973; a deep and supple 1971, and a big, brawny, complex 1970. Because of the lack of publicity this chateau gets, in addition to the wide supply of different vintages available, consumers can easily find Meyney in years back to 1962. Locally, Central Liquors and Chevy Chase Liquors carry the biggest selections, although Meyney generally can be found in most of the city's wine shops. Wine Briefs

Throughout Europe's wine regions, there is great optimism that 1982 will be a special year. Crops are quite large in virtually every major viticultural area, and early reports indicate the quality is good, perhaps even exceptional. In France's Burgundy region, the white wines made from the chardonnay grape are considered particularly fine. Further south in Beaujolais, the wine is considered variable, but generally well above average. The nouveau wines will be on the market by November 15, so consumers can find out for themselves.

In Bordeaux, the crop was very large, but harvested in good weather, and the grapes were said to be fully ripe. Several very reliable chateaux owners have said the vintage is large and excellent, with deeply colored, full-bodied, very rich and tannic wines produced throughout the major regions. Anthony Barton, the erudite proprietor of Chateau Langoa-Barton and Le'oville Barton, and generally quite conservative in his vintage assessments, said last week that the quality of the bordeaux harvest was "simply spectacular." No doubt the vintage is very good, but just how good cannot be determined until the wines have finished fermenting and settled down.

In spite of all this trade enthusiasm, it will not be until next spring that formal evaluation of the wines' quality can be effectively carried out. However, the news does seem very, very good. In view of the reported quantity and quality of the 1982 European harvest and the continued strength of the American dollar, European wine imports should represent the best values on the market.