Nosocomial myiases can be an important condition from a public health perspective. However, cases of this condition reported in regional and worldwide biomedical literature are scarce.A case of nosocomial myiasis is reported from Costa Rica, where the species involved was Lucilia cuprina (Diptera: Calliphoridae).A 91-year-old patient with signs of immunosuppression, severe impairment of lung function, and mechanical ventilation presented larvae in both nostrils on the seventh day after admission. Five specimens were collected and processed for identification.The taxonomic identification of the specimens established that the muscoid fly species was L. cuprina.This is the first case of nosocomial myiasis reported from Costa Rica and in Latin America for which the etiological agent is L. cuprina.