We report an outbreak of pigeon mite infestation involving two patients, two nurses, and one physician on a medical ward in a municipal hospital. The index patient developed a diffuse, pruritic erythematous maculopapular rash on his trunk and extremities. Dermanyssus gallinae, a nonburrowing, blood-sucking avian mite was identified on the patient and his bedding. A second patient who complained of scalp pruritus had mites present on her pillow and bed linen. The intern taking care of both patients, and two nurses who had contact with these patients, had mite infestation. Pigeons roosting on the air conditioners and near the doors connecting the patients' rooms to a sunporch were the source of the mites. The outbreak abated after control measures were instituted that prevented pigeons from roosting on the porch. This outbreak illustrates an unusual cause of nosocomial pruritic dermatitis that may be misdiagnosed as scabies or pediculosis. Physicians and health care personnel working in metropolitan areas are alerted to mites as a cause of pruritic dermatitis that may be chronic, recurrent, or unresponsive to ectoparasiticides.