Security guards at the Children's Hospital Medical Center in Boston walked off from their jobs last Friday and set up obstructive picket lines outside the hospital.

The guards are striking the hospital, which is associated with the Harvard Medical School, because it has refused them permission to unionize and has denied their request that they be allowed to carry guns when working outdoors at night.

"The issue is whether or not the hospital can effectively deny to their employees the rights guaranteed to all American citizens-the right to organize into unions," Edward T. Sullivan said yesterday. Sullivan is an official of Local 254, Building Service Employees International Union, which is attempting to organize the policemen.

Sullivan said that university and hospital trustees are conspiring to prevent the state's 46,000 hospital employees from organizing. He also accused the Children's Hospital administration of unfair labor practices, such as harassment of picketers and spying. He has filed a complaint with the Massachusetts Labor Relations Board.

Would Be Chaos

"We will bargain with all 425 general service employees collectively, but wefeel it would be chaos to have to deal with dozens of employee groups separately," William J. Brennan, the publicity director of the medical center, said yesterday. Brennan added that the union has not approached the hospital with a proposal for unionizing all general service workers.

The hospital has also filed a complaint with the State Labor Relations Board, charging the security officers with violation of a Massachusetts law prohibiting non-medical hospital employees from engaging in strikes or work slowdowns.

"We had the legal right to dismiss these men from the payroll the minute they walked off the job, but we didn't because we felt they were on an emotional binge," Brennan said.

The security guards on strike, 22 out of a total force of 28, say that they are blocking delivery only of non-essential items, and are not obstructing delivery of medical supplies needed for hospital patients.

A spokesman for the Harvard Medical School said that the Children's Hospital has its own administration, and that Harvard is not in a position to take any action in this dispute.