An ongoing strike of clerical workers threatens to disrupt Boston University, even though B.U. students returned to classes last week as scheduled.

District 65, Distributive Workers of America, struck for 19 days last spring to gain recognition. After summer-long negotiations proved unsatisfactory, the local voted to strike Friday.

Lately

"While students have been at classes, most are not registered properly," A. Carol Knox, chairman of B.U. local 65, said yesterday.

"The effect of a clerical strike is extremely cumulative," she added, referring to a backlog of paperwork building up at B.U.

District 65 is in the preliminary stages of organizing clerical workers at the Harvard Medical School after a two-year hiatus.

Medical Area workers voted to reject District 65's bid to represent them in July 1977 after a three-year campaign by the union.

The University had waged an informational publicity campaign in its ultimately successful effort to block the union.

"While we all know Harvard is richer than B.U., many of the issues are the same," Knox said, adding union organizers at Harvard are enthusiastic about the progress made by the local at B.U.

Among the key issues are the wage scale, health insurance benefits and the definition of the union. B.U. president John Silber announced Friday the university's first offer will stand unchanged.

Chief B.U. negotiators Leonard Costa and Robert A. Bergenheim were unavailable for comment yesterday.

Union members said they expected negotiations to resume early this week.

The local is seeking modified union shop status under which present clerical workers could choose whether to join, and new workers would have to join District 65. The administration rejected this proposal.

B.U. negotiators refused to submit to binding arbitration last week.

"There is a movement building here, supported by the students--an awareness that B.U. is attacking all unions," Knox said.

The administration's wage proposal is a $200 cash bonus coupled with a 35-cent-an hour raise the first year of the contract, and an additional 35-cent-an-hour raise the second year.

"We're the university's lowest-paid workers in wages and health insurance," Knox said.

Most workers were optimistic that the strike would end soon. "Things at the school seem to be running on schedule, but much of the internal paperwork has slowed down," union member Judy Riordan said yesterday.

The B.U. faculty, which settled with the administration last spring after a strike, has had trouble since then, Knox said. "B.U. has ignored the contract--almost every grievance has been sent to arbitration," she said.

"So even if we settle on a contract, it looks like it won't be our last struggle," she added