Although the president-elect has promised to stop it, and the United States Supreme Court may yet declare it unconstitutional, draft registration began again last week.

Protesters organized by the Boston Alliance Against Registration and the Draft (BAARD) marched on post offices in Cambridge and Boston, clashing several times with police, who arrested a total of 44 people through last Saturday.

While Selective Service System spokesmen predicted that 98 per cent of the 1.9 million 18-year-olds required to register would indeed sign up BAARD members said the statistics do not matter. "This is the beginning of an anti-war movement to prevent the next war, not just to end registration," Frank Broadhead, BAARD's director, said at Saturday's demonstration in Harvard Square.

Broadhead's troops tried unsuccessfully to close down the Mt. Auburn St. post office on Saturday, as more than 30 postal inspectors and federal guards teamed up to keep the doors open.

Elsewhere in the country; police reported only scattered protests. Vandals sacked post offices in Los Angeles, and officials arrested sit-in participants in New York and Chicago, but "generally things went smoothly," Brayton Harris, assistant director of Selective Service, said yesterday.

Harris and his boss, Bernard D. Rostker, may soon be making paper airplanes with all of their registration cards, however, if Ronald Reagan follows through on his campaign vow to eliminate registration--a program he has called "a meaningless gesture." Reagan has not clarified his plans for Selective Service since the election.

Meanwhile, Harris said Selective Service and the Justice Department will not worry about catching the estimated 200,000 19- and 20-year-olds who failed to sign up during last summer's initial round of registration until Reagan commits himself one way or the other.