Vibrio alginolyticus is a microorganism of marine environment which occasionally may cause infections on man. We described four patients with external otitis who had prolonged contact with sea water presented itch and seropurulent fluid. V. alginolyticus was isolated by pure culture from ear fluid of three of them and associated to V. fluvialis in another. The administration of ciprofloxacin in three cases, and ceftazidime in the other succeeded in the remission of the symptoms.