Arlington Del. Elise B. Heinz, a Democrat who attempted to use her support for the Equal Rights Amendment to retain a seat in the Virginia House of Delegates, and Fairfax Del. Martin Perper, a maverick Republican, were defeated yesterday in bitter primary contests in Northern Virginia.

Heinz, 46, a Harvard-educated lawyer who was one of eight women in the 100-member House, and Perper, 42, who was sometimes at odds with party leaders, were the only Northern Virginia incumbents unseated in 10 primaries in the Washington suburbs. Both Heinz and Perper were seeking third terms in the state legislature.

"I lost, I'm sorry I lost, and that's all I've got to say," said Heinz, who challenged Arlington's three other incumbents after her Arlington-Alexandria seat was abolished because of population losses in the inner suburbs.

Perper, a wealthy businessman who operates several area motels, blamed a campaign letter linking him with "homosexual activists" for ending his four-year legislative career in Richmond. "It was a bunch of rubbish," said Perper, who had defied GOP leaders by challenging Independent Sen. Harry F. Byrd Jr. in the 1976 elections. "But that's politics. You win some and you lose some."

Unofficial returns showed that the other 13 incumbents facing primary battles in Arlington, Prince William and Fairfax counties yesterday won the right to run in the Nov. 3 general elections. Winners in those races will serve a one-year term in the legislature, and will be charged with helping to unravel the state redistricting plan that was declared unconstitutional by a federal court two weeks ago.

Republicans in Fairfax County outvoted Democrats by 2-to-1 in the populous McLean-Falls Church area, where one of the most hotly contested primaries was fought. Del. Vincent F. Callahan Jr., who led the GOP ticket there, pointed to the heavy Republican turnout as evidence of continued Republican gains in the rapidly growing Fairfax suburbs.

"I think the turnout in the Republican primary compared to the Democratic primary shows this area has turned the corner," said Callahan, Northern Virginia's senior GOP legislator. "It bodes well for us in the fall."

Party officials said the traditionally low turnout for primary races, compounded by confusion over the state's contested redistricting plan, appeared to favor incumbents, who had better organizations and higher name recognition.

Former state delegate Robert Thoburn, who was thwarted in a bid to regain a Fairfax seat he lost two years ago, said the low turnout worked against him. Thoburn, a conservative, blamed crossovers by Democrats, who had no primary in his district and voting by public school teacher -- "a special interest group" -- for his defeat.

"I think the name of the game in primary elections is getting your friends out to vote," said Republican Del. James H. Dillard II, a school teacher and one of the victors in Thoburn's district. "They have their friends coming out and we have our friends."

Final, but unofficial returns in 10 area primaries showed:

Del. John S. Buckley, 28, youngest member of the Virginia legislature and a political consultant, led the Republican primary in northwestern Fairfax's 50th House District. Buckley will run in November with George C. Landrith Jr., 39, a former precinct chairman in the Reagan campaign, and incumbent Del. John H. Rust Jr., a one-term legislator who formerly served as Fairfax City's attorney.

They will face in the fall elections Democrats Kenneth R. Plum, a former legislator, and Del. Dorothy S. McDiarmid, the county's senior Democratic legislator, who were nominated without a primary.

Del. Lawrence D. Pratt, a Capitol Hill gun lobbyist, led the field in the GOP primary in southwestern Fairfax's 51st District. He will be joined on the ticket by Dillard, a moderate who had been challenged by more-conservative elements in the party, and Del. Robert E. Harris, a Washington executive of an aerospace company and four-term incumbent.

In the fall they will face M.J. (Mike) Hershman, Vivian Watts and V.L. (Lee) Strang Jr., who were nominated without a primary.

Del. Mary A. Marshall, 60, who has served seven terms in the statehouse, led in Arlington's Democratic primary. She was followed by Dels. Warren G. Stambaugh, 37, a member of the House since 1974, and James F. Almand, 32, a lawyer who is seeking his third term. Heinz lost in the race to Almand by a margin of 660 votes.

The three Arlington Democratic incumbents will face Theodore A. (Ted) Lattanzio, 34, an employe of the National Rifle Association's Institute for Legislative Action, who drew the most votes in the county's Republican primary. Also nominated by the GOP there were E. J. (Jay) Jarvis II, an insurance underwriter, and Georgia A. Delyannis, 48, a longtime GOP activist.

Elaine A. Lailas, 42, a teacher at Northern Virginia Community College, led Democrats in Fairfax's 49th House District. She, Conrad J. Marshall, 43, an attorney, and Flora M. Crater, 67, founder of the Virginia Women's Political Caucus, will face Republicans Callahan; Robert T. Andrews, 61, a lawyer, and Gwendalyn F. Cody, 59, a Fairfax GOP party official, who were winners in the race that Perper lost.

Frank Medico, 57, a certified public accountant, drew the most votes in the Republican primary in southeast Fairfax County's 52nd District. Del. Warren E. Barry, 48, a 12-year veteran of the House, and Ben Partin, 55, a retired Air Force general and member of the county GOP executive committee, also won nomination.

Del. Gladys B. Keating, 58, an incumbent seeking her third term, led the field in the district's Democratic primary. Brendan P. O'Hara, 24, former campaign worker for Sen. Edward M. Kennedy (D-Mass.), and David L. Temple Jr., 34, a public school principal who was the only black legislative candidate in Northern Virginia, also won nominations.

Del. David G. Brickley, 37, a mortgage banker, received the most votes in Prince William County's Democratic primary. Del. Floyd C. Bagley, 59, an attorney and member of the House since 1976, and attorney Norborne P. Beville Jr. of Nokesville also won nominations for the county's three House seats.

They will face William J. (Bill) Becker, who works for a government consulting firm and led the balloting in Prince William's GOP primary. Harry J. Parrish, 59, the mayor of Manassas, finished second in that race, followed by Jack Rollison, 31, president of a local tire company.

Most of the interest in the primaries had focused on the Arlington Democratic primary, where the four incumbents were competing for three seats. Several women's groups that had backed all four delegates in the past shifted support to Heinz, an action that angered the three other incumbents who said they, too, had championed passage of the ERA in the conservative Virginia House.

Of the six primary races in Fairfax, the bitterest struggle occurred in Fairfax's 49th District. Republican challenger Claiborne B. (Buck) Morton drew sharp criticism for a remark that "we'd be better off if only Christians were elected" to public office.

Morton, who first admitted making the remark and later denied it, claimed Perper had helped leak the information to the press in an effort to discredit his campaign.

According United Press International, the only other incumbent to lose in Virginia's legislative primaries yesterday was Del. Howard E. Copeland, a one-term Democratic legislator from Norfolk. A lawyer, Copeland was also attempting to retain a seat in a jurisdiction which had lost a seat because of declining population.