Efforts by the Organization of American States to hold its general assembly this June in the sunny Caribbean are clouded by logistical logjams, not the least of which is a shortage of chairs for diplomats of the 25 member nations.

Grenada, the newest and smallest of the OAS nations, invited the organization last year with what is now looked upon as an over-optimistic outburst of hospitality.

When it developed that there were not enough chairs on the island to accommodate the visitors, the government decided to apply for emergency U.S. assistance in the form of 750 chairs.

With a population of about 120,000 in an area twice the size of the District of Columbia, Grenada is too small to have its own U.S. AID office 2d sheet so application was made in nearby Barbados.

The State Department passed that issue on to the OAS. Next Grenada asked Japan to provide autos for transporting the foreign ministers from hotels to the meeting site. Since Grenada has hardly any international communications, a request went out for Telex and telephone facilities.

Delegates at the OAS Permanent Council in Washington began to suspect that Grenadan Prime Minister Eric M. Gairy was using the assembly to refit his island. Gairy was ousted from office by the British in 1962 for misappropriation of funds but was reinstated and he has ruled since independence in 1974.

In a recent progress report to the OAS council, Grenada's representative announced that preparations for the June 14-24 assembly have moved "into top gear with the arrival of a technician from the U.S.A. . . . to to assist in constructing a geodesic dome" that is to house the plenary sessions.

Representative Alfredo Neira said air transport problems, including the lack of an airport that can handle commercial jets, have been "eased" by reserving space on the scheduled LIAT Airline flights for three days before the opening.

To answer concerns about medical facilities, Neira reported that the hospital in the capital, St. George's, three miles from the assembly site, has an operating room "headed by an English surgeon." He listed other services, including drugstores, and noted that "patent medicines also are sold by supermarkets."

There have been rumors of a shift in the meeting site, but it now appears, that another solution is being considered. Under this plan, much of the annual meeting's work would be done at a preliminary meeting in Washington, with a short, ceremonial, document-signing session in Grenada.