Representatives for the striking Washington Opera Chorus have reached a tentative agreement with the Washington Opera, and will recommend the new four-year contract to its membership next Monday.

Approval of the new package would end a three-week strike, and the chorus has been asked to attend a rehearsal Sunday "as an act of good faith," according to the chorus's legal representative.

The strike, which is believed to be the first of the chorus in the company's 35-year history, did not cause any disruption of the company's season, which is scheduled to open Nov. 3 with the chorus-less opera "Salome" by Richard Strauss. The chorus is scheduled to perform in "La Boheme," opening Nov. 10.

The company and the chorus, which belongs to the mid-Atlantic region of the American Guild of Musical Artists (AGMA), reached the tentative pact early yesterday at the Kennedy Center.

Officials of the opera company declined to provide details of the settlement but sounded upbeat in a memo to the staff. "We are very pleased to advise you that last night the Washington Opera and its chorus reached a tentative settlement," wrote Edward Purrington, administrative director of the opera, the resident company of the Kennedy Center. "No further details until the chorus has ratified the agreement. Now let's all make music!"

Joshua Kaufman, the national representative for AGMA, was cautiously optimistic. "I believe this is a good settlement in the classic sense of the word. No one walked away perfectly happy but certainly great gains were made by AGMA," he said.

The negotiations involved the basic pay for rehearsals and performances, overtime pay, the length of rehearsal and the rate for playing a musical instrument, among other issues.

The company had proposed a rehearsal rate of $11 an hour and a performance rate of $90 for the first year of the four-year contract. The union initially asked for $15 an hour for rehearsals and $110 for performances but at the time of the strike vote agreed with the company's proposal for the first year. The differences pertained to the later years of the contract.

The old contract, which expired at the end of last season, provided $9.10 for rehearsals and $78.30 for performances.

In preliminary discussions, the chorus and the company had agreed to an increase in overtime from time-and-a-quarter to time-and-a-half and had agreed to increase the rehearsal call to a minimum of three hours. Also, the two parties had agreed that a chorister would be paid $20 extra if the person played any musical instrument in a performance.

For the upcoming season, the company has contracts with 105 singers. The "Boheme" production has 48 choristers. All the members of the local AGMA who worked for the company under the prior or present contract are eligible to vote Monday.