Three new periodicals are being produced in Washington for diverse audiences -- investors, persons who follow local business and residents of the growing Middle Atlantic region.

Leading the pack is a new evolution of the familiar Regardie's Real Estate Washington. Executive Editor Bill Regardie has taken what he says is a successful magazine and expanded it into Regardie's Business and Real Estate Washington (subscription for six issues a year is listed at $25, with a single newsstand price of $5).

The premiere September/October issue was scheduled to hit the street at various newsstands this morning. A November/December issue also is planned this year and Regardie plans monthly publication starting in 1981.

In an interview last week, Regardie said of Real Estate Washington that it was "somewhat unrealistic to attempt to isolate real estate from the larger business community." The real estate market was beginning to stumble from the weight of recession and tight credit, causing Regardie to think a self-preserving change was in order.

Thus was born Regardie's Business and Real Estate Washington.

"Real Estate Washington was not that entertaining," Regardie said. "It wasn't what I wanted so I went out and found a sensational assistant editor, now editor, Henry Fortunato, and got absolutely the best people I could. I've tried to produce a piece of entertainment. The overriding philosphy behind the [new] magazine is to make it is a person would rather read it than anything else."

The first issue owes a lot to its predecessor, both in style and content. Regardie has retained many of his previous columnists, and added regular features on stocks and automotive-related concerns. Each edition of the magazine will have a "battle story" about the struggles that occur when established business are confronted with new rivals in the Washington markets. e

Today's battle story focuses on the "deadly serious" threat facing the area's established do-it-yourself auto parts shops -- Pep Boys, Hi Gear and Penn Jersey -- from Dart Drug's new subsidiary, Trak Auto.

The magazine's cover story is about attorney Kenneth Michael Robinson. "It's about the business of lawyering," Regardie said.

Other stories in the first issue include an essay on the success of radio station WAVA-FM since a new musical orientation early in 1979; an article on corporate adviser Walker Lewis, the "prophet of profits," and an interview with Washington Post Publisher Donald Graham.

A new entry in the leisure time and country-living genre is Country Magazine, a monthly with headquarters in Alexandria. According to publisher Walter Nicklin, Country Magazine will "do for the Mid-Atlantic region what publications like Yankee and Blair & Ketchum's Country Journal have done for New England."

The magazine, scheduled for release at the end of the month, is off to a flying start, with a base circulation of about 30,000 subscribers hooked by Country's direct mail search for buyers. The first press run, slated for later this month, will be 35,000 copies, with newsstand sales expected to picking up any slack in subscription sales. (A subscription for 12 issues a year is offered in the first issue for $10. Subsequent subscribers will face a $15 annual toll.)

Country Magazine was a proven hit with readers before Nicklin committed himself to full production, but he had a hard time finding partners. Nicklin tested his market reaction with a sell-out pilot issue about three years ago and then started searching for investors to help share start-up costs for the magazine. He finally found a dozen.

"The only thing that would limit us is the size of the universe," exclaimed Nicklin, while conceeding that the mid-Atlantic region is not big as far as universes go. "The unifying thread is the idea of the countryside surrounding the large urban centers," he added.

"There is," Nicklin said, "clearly an audience out there that is interested in the area as a region. The trick, of course,is whether you deliver the editorial product the people want."

Nicklin says that his editorial product will include stories on regional current events, sports, and the area's history. The first issue is highlighted by an article titled "Saving the Bay" by Sen. Charles Mathias (R-Md.). Other stories include a guide to the city of Frederick, a hiking story set in the Shenandoah wilderness and a tale of a country auction.

Filling out the threesome is the rather unorthodox Journal of Investing, written and published by financial consultant Barry Goodman of Leopold & Linowes. CPAs. His 16-page magazine contains not a shred of advertising, and evolved from what used to be Goodmans's personal newsletter to his private clients.

The Journal reads like a texbook, throughly instructing the reader not only on market conditions concerning the stock market, the bond market, real estate, oil, foreign currency and precious metals, but also on Goodman's advice in all these investment areas.

"The only thing I've seen so far," said Goodman, "are specialized newsletters that concentrate on specific topics. What I want to do is allow to get an overview on all investment modes. The Journal is a magazine with an integrated format that attempts to be more advisory than most others."

Goodman has set up his magazine so that one section may refer to others, encouraging his subscribers to read the entire issue. And he takes nothing for granted, patiently leading the reader through explanations of just what economics is, how economists try to predict the financial future and how inflation and recession work.

"It's a stopgap for people who are uncertain about which investment route to take," claimed the author.

The Journal of Investing is the one new magazine that won't be found on the streets. The first issue had a press run of just 100 copies, and Goodman is waiting to see if his experiment will find an audience.

Subscriptions are available from Goodman for $49, which buys 7 issues annually.