In what was described by one participant as "trick-or-treating for adults," 1300 of Harvard's mid-level bureaucrats kibitzed and gorged themselves yesterday at the University's biannual employee fair.

Below the dour, stone faces of famous Harvard benefactors, representatives from 30 University agencies gathered in Memorial Hall to eat donuts and popcorn, meet each other and tell each other what they do all day in their offices all around Harvard.

The Harvard Managers Exchange (HME), a group of University administrators, started the five-hour- long fair in 1978 to improve interagency communication.

Harvard is so decentralized that the fair was created to prevent each agency from "reinventing the wheel," said Doug Renick, coordinator of the fair and manager of training and development.

Besides swapping tales from the office, the revelers, numbering roughly the same as in five past fairs, consumed 1200 cups of cider, 12 trays of brownies, 70 dozen cookies and 300 donuts, said Food Services Supervisor Andrea K. Swift.

Participants wandered down aisles of bright yellow booths, played with computers, watched demonstrations, entered raffles and collected brochures and knickknacks. Most agencies designed creative displays and gave away little prizes to call attention to their resources.

"We've decided that it's trick or treating for adults," said Henry L. Lussier, a marketing associate for the American Repertory Theater. "I think it's been great," he said, noting that he could not keep up with demand for brochures and free buttons.

"[The fair] is a lot fancier this year," said Martha K. Baldwin, work-study coordinator for the Student Employment Office. "Every time they have it, each booth gets fancier."

The fanciest booth, as judged by a HME committee, belonged to the Office of Information Technology. Also the largest, it had demonstrations of several computers and a satellite television system.

Second place, for the second consecutive year, went to the Department of Environmental Health and Safety (EHS), whose booth featured displays of several large household insects.

"Every year [the EHS] wins second place, and all they have is a couple of bugs," said Harvard University Police Sgt. Larry Fennelly, whose booth adjoined the EHS booth. The police booth demonstrated the prototype of a computer security system that emits a loud noise when the computer is moved.

"All you have is a computer that beeps," quipped an EHS official.

The Patents, Copyrights, and Licensing booth advertised "invention advice" for 5 cents and featured a collapsible geodesic dome made of coffee-stirrers and dental floss a wind-up jumping mouse that went up in the space shuttle, and a coin bank whose skeletal, green hand emerges from inside to snatch pennies.

By the end of the day, the pale hand had been stilled, its batteries worn out by too many demonstrations. "Poor fella," said David Stein, who manned the booth. "I didn't realize my poor animals would suffer."

The Harvard Fair adds to the camaraderie of the management community, said Sheila Peterson, a staff assistant with the Harvard Dental School, who was attending her fourth fair. The school gave away toothbrushes and enlisted participants for a free teeth cleaning