The woman, a resident of Hardoi district, about 100 kilometres from Lucknow, was at the hospital with her husband for a few days, who underwent a surgery a few days ago.
The woman has alleged that on Tuesday night a liftman at the hospital, Vinay, invited her to have dinner with him. He then forcibly took her inside a lift with the help of a security guard and another person, she claims.
The woman alleges she was raped inside the lift and threatened to keep quiet by the three men.
Police say the woman, who approached them this morning, has been sent for a medical examination, and that the two other accused will be arrested soon.