A well-behaved me'doc, as everyone knows, is supposed to be red. Not a single white wine was deemed worthy of inclusion in Napoleon III's 1855 classification of the Me'doc. The Me'doc is also the home of Chateaux Lafite Rothschild, Margaux and Mouton Rothschild, perhaps the most famous red wines in the world, as well as a high percentage of the other well-regarded red bordeaux. To most of us, "me'doc" means claret: well-structured, long-lived -- and red.

Meet the white wines of the Me'doc.

Experienced wine drinkers are often surprised to discover that white me'docs exist at all. And indeed, white me'docs share a very different lineage from their red cousins.

Red me'docs are made from a blend of thick-skinned black grapes, usually cabernet sauvignon, merlot and a few other varieties. Vinified off their skins, such varieties might be able to yield white zinfandel-like "blush" wines -- more like rose's really.

The me'doc whites, however, are true white wines. They are made from white grapes, such as the sauvignon blanc and semillon, which also happen to be the principal grapes of the Graves region just to the south. Unlike white graves, however, white me'docs are true rarities, representing a minuscule percentage of total Me'doc production.

The white me'docs offer a fascinating comparison not only with white graves and other white bordeaux, but also with the red wines produced at their parent chateaux. Many claim to detect in them the distinct gou t de terroir (taste of the soil) associated with red me'docs. And though dry, they tend to be less austere and more elegant than white graves.

Listed here are the commercially available white me'docs. Despite their rarity, they are generally reasonably priced and in good distribution. Prices range upward from $5.

Pavillon Blanc du Chateau Margaux ($35): A pet project of Corrine Mentzelopoulos, whose family orchestrated the dramatic revival of first-growth Chateau Margaux's red wine commencing with the 1978 vintage. Although Pavillon Blanc has been made at Margaux for most of this century, the decision to sink millions of additional francs into increasing its production has provided a strong boost to the image of white me'docs generally. The goal at Margaux is to produce a white wine with the elegance and breed of its magnificent red wine -- and Pavillon Blanc's quality clearly reflects the extraordinary care lavished on its production.

Made from 100 percent sauvignon blanc grapes grown on a 30-acre plot set amid the chateau's extensive cabernet and merlot vineyards, the wine is barrel-fermented at low temperatures in a unique, specially refrigerated chai. It is aged in new oak for six months and then in bottle for an additional year before release.

At $30 or more, Pavillon Blanc is priced head-to-head with the two great white graves, Haut Brion Blanc and Laville Haut Brion. The contrast in style, however, could hardly be more dramatic. Where the graves are powerful, earthy and pungent, the Margaux is crisp and fruity, with a subtly perfumed, oak-scented bouquet. The 1978 and 1979 vintages are ready to drink now, but the 1981 and 1982 releases would benefit from additional cellaring.

Ironically, despite the first-growth status of the parent chateau, Pavillon Blanc, like all me'doc whites, may only be labeled with the lowest appellation controle'e, "Bordeaux Blanc."

Caillou Blanc du Chateau Talbot ($8-$10): Chateau Talbot in St. Julien is famous for its full-bodied, emphatically flavored red wine, and this style is largely carried through in its white wine. Caillou Blanc derives from a small plot of white grapes planted by Georges Cordier, the father of the present owner of Chateau Talbot, Jean Cordier, in 1930. Previously produced only for the House of Cordier's private cellar, shipments to the United States did not begin until the 1979 vintage.

Caillou Blanc reflects a very different wine-making philosophy from that of Pavillon Blanc du Chateau Margaux. Not intended for aging, it is kept away from wood completely in order to gain a fresh, fruity character from its 100 percent savignon blanc cepage. Though more graves-like than Pavillon Blanc du Chateau Margaux, it nevertheless tends to be rounder and less flinty than a typical graves. Quite well-made, as one would expect from a Cordier wine, Caillou Blanc represents a novel and well-priced alternative to the more familiar graves.

Chateau Loudenne ($5-$8): Located just beyond the northern border of St. Este phe, this British-owned property is perhaps the only Me'doc chateau where production of white wine represents more than a sideline, accounting for nearly 20 percent of total production. With a much higher percentage of semillon grapes (50 percent sauvignon and 50 percent semillon) than Margaux and Talbot, Loudenne Blanc is fruity and soft, resembling a softer-styled graves.

Chateau Lynch Bages: Only a tiny amount of white wine is produced at fifth-growth Chateau Lynch Bages in Pauillac, from mostly semillon blanc grapes. Unfortunately, the small quantities make commercial distribution impossible. A visit to the chateau, however, has been known to permit a successful plea for a taste from the Cazes family's private stock.