Boston police are holding without bail an unidentified man allegedly connected with five armed robberies, one of which took place in a Harvard building in the Medical School-Children's Hospital complex, and five rapes.

The man was arrested last week for trespassing in Children's Hospital. Hospital security forces turned him over to Boston police, who found warrants for his arrest outstanding in three city districts on charges of armed robbery and rape. Police are now holding him on a rape charge.

Since his arrest, four rape victims have positively identified him from photographs as their attacker, Harvard police officers said yesterday.

"Of four known rapes in that area in the past few months, all are now accounted for by these IDs," Harvard Police Sgt. Richard W. Smith said last night "I feel that at this time, that particular problem has been resolved."

Smith added that a woman who was robbed in a Medical School building will fly to Boston to identify the man.

The armed robbery at Harvard was the subject last August of a crime bulletin issued by the Harvard Police in reply to rumors concerning incidents in the complex. The bulletin described the man as a black male about 26 years old, weighing 160 pounds., 5 ft. 10 in. tall with a mustache and goatee.