We present two cases of nosocomial myiasis that occurred in Costa Rican hospitals. In both cases the etiologic agent was identified as Blaesoxipha plinthopyga (Diptera: Sarcophagidae). The first case occurred as an infestation of a surgical wound associated to abdominal surgery in which maggots were observed in the purulent material of the wound. This case required an exploratory laparotomy, in order to dismiss the presence of more larvae, and peritoneal washing. The second case was associated with a patient in an intensive care unit and under suspicion for salicylates poisoning. She was intubated to provide assisted mechanical ventilation. The patient spontaneously expelled several maggots from her oral cavity, which then required an endotracheal aspiration and more larvae were obtained. In both cases the maggots were mature third instar larvae, evident within five or more days after admission of the patient in the hospital, which typifies both cases as nosocomial myiasis.
