Fairfax County attracted only two bidders yesterday for one of its most highly touted assets--the right to provide cable television service to the wealthy suburban community.

County officials expressed disappointment that only two firms--and only one with national cable experience--offered to build cable systems in Fairfax, which has long been described as one of the most potentially lucrative markets in the nation. By contrast, Prince George's and Montgomery counties in Maryland recently attracted eight bidders each for their cable franchises.

The two bidding companies--Fairfax Telecommunications Inc. and Media General Inc.--boast some of the county's most prominent builders, developers and lawyers as local investors--among them Virginia State Sen. Adelard L. Brault, Democratic dean of the Fairfax delegation.

Fairfax Telecommunications, which includes Brault as general counsel, is a partnership between about 140 local investors and the giant Denver-based Tele-Communications Inc. The competing Media General owns newspapers and television stations in three cities--including Richmond--but only one cable system, in Fredericksburg, Va.

Several major firms dropped out of the Fairfax competition in recent months, objecting to the amount of detailed information the county was demanding about exactly who owns the companies and their capability to come up with the $100 million needed to build the system. Another firm dropped out yesterday, claiming that a recent U.S. Supreme Court decision has clouded the county's ability to promise an exclusive franchise.

Some county officials speculated privately yesterday that cable firms may be hoping to pressure the county into rejecting its two bids and trying again--after relaxing its cable requirements. Others blamed the low turnout on a combination of factors that include competition from Montgomery, which accepted bids only a few weeks ago, high interest rates, general retrenchment in the cable industry and the expense of providing cable to Fairfax's widely dispersed 200,000 households.

Both companies that bid promised to spend more than $100 million in Fairfax during the next 15 years, offering more than 100 channels of sports, movies, children's shows, local government meetings and other programming. Fairfax Telecommunications rented a panel truck yesterday to cart its boxes of color-coded proposals to the county administration building in Fairfax City.

Fairfax County and its hired consultant will evaluate the proposals during the next four months and the Board of Supervisors could award a franchise by July 1. In that case, some homes could expect cable by 1983, with the entire county wired within five years.

The board could also decide that neither proposal is acceptable and readvertise for bids.

"My reaction to that would be violent, and probably not quotable," said L. Gary Byrd, engineer, past president of the Fairfax Chamber of Commerce and president of Fairfax Telecommunications. "We've proposed the same system we would have proposed if every company that has come and gone was still lined up at the door. We haven't diminished it in any way."

Fairfax Telecommunications, whose local investors range from Democratic lawyer C. Douglas Adams to Republican adviser Edward S. DeBolt, promised annual programming grants for the Fairfax Symphony, the county Women's Network and other organizations as well as yearly stipends to encourage economic development and help solve the county's traffic problems.

The company would charge subscribers $6.95 a month for 89 channels, an additional $6.95 for Home Box Office and other movie channels, $5.95 more for two-way television services and a $29.95 installation charge.

Media General, whose five local investors include builder Herbert L. Aman III, developer Edwin W. Lynch Jr. and real estate businesswoman Suzanne H. Paciulli, also promised support for community organizations. The company would offer 93 channels for $8.95 a month or 126 channels plus two-way, interactive television for $10.95, plus Home Box Office for an additional $7.95.

Both stations also promised a basic monthly service for less than $3. Media General said it would make up for its limited cable experience by consulting with Prime Cable Corp., an Austin-based firm with franchises in Annapolis, Dumfries, Va., and other communities around the country.

"It obviously would have been better to have more bidders," Board Chairman John F. Herrity said. "I think it's the money market more than anything that's causing the problem, the cost of money."

Community Cablevision of Fairfax Inc., a local firm, yesterday joined a handful of larger firms that studied Fairfax and then declined to bid. Arthur Barber, general manager of the company, said his firm withdrew because Fairfax could not promise an exclusive franchise. "If there's any competition, the $100 million is lost," Barber said.

The Supreme Court recently ruled in a case from Boulder, Colo., that jurisdictions are not necessarily exempt from antitrust suits brought by competing cable firms.