Hotel room vacancies in Cambridge during Commencement Week next June are already very limited, and one hotel is booked solid during the graduation period for the next two years.

The Harvard Motor House has reserved all of its 72 rooms for the nights of June 15 and 16 (Commencement next year is June 16) and was filled up over six months ago. They are also booked for the night before and the night of graduation in 1978.

Sold Out

When asked about available rooms for Commencement Week, Ellen Aronovitz, reservationist at the Holiday Inn near the Law School on Mass Ave, said yesterday, "That's a joke. We sold out for the nights of the 15th and 16th two or three months age." The hotel won't take any reservations for 1978 until next July, however.

The Sheraton Commander is also filled, but requires a deposit by December 15 to hold the reservation. If deposits are not received, the hotel will take new reservations at that time, Joseph Sheerin, desk clerk, said yesterday.

The Fenway Howard Johnson also has no vacancies for the night of June 15. "Usually what happens is that rooms open up in April, when we get cancellations," Sandra Brent, reservations manager for the hotel, said yesterday.

However, rooms still can be found within the city limits. The Hyatt Regency in Cambridge reported only about a fourth of its rooms reserved for the night before Commencement. This may be because the Hyatt only opened this September and is relatively large, with 500 rooms.

The Kirkland Inn only reserves a few days in advance, so it should have vacancies until the beginning of June. It houses about 100 people.

Several hotels contacted yesterday in Boston, including the Ritz-Carlton, Bradford, Colonnade, and Copley Plaza said that they still have rooms available for June 15 and 16