A retrospective survey was carried out on the epidemiological monitoring of the isolation incidence of Mycobacterium marinum in 21 laboratories, in an attempt to gain an insight into the frequency of its isolation in Spain. From 1991 to 1998, 39 cases (22 male and 17 female) of bacteriologically confirmed M. marinum infection were accumulated. The majority of the cases (35) were fish related. The clinical presentation usually suggested sporotrichosis, with the majority of skin eruptions appearing on the hand (32 cases). For treatment, minocycline was recommended as the drug of choice in 12 cases, rifampicin in eight cases and clarithromycin and ethambutol in seven cases.