Outbreaks of legionnaires' disease (LD) in tourists visiting Italian and Spanish resorts have been recently reported. An unusual number of reports of LD in tourists visiting the US Virgin Islands prompted an investigation of risk factors for development of LD in this area. Twenty-seven cases of LD were identified between 1979 and 1982 through press reports, personal communication, the national LD surveillance system, a review of hospital records, and a mail survey. Twenty-four of 27 persons with the disease had visited St Croix and 12 of them had stayed at a single hotel in 1981. Available evidence suggested that infection was due to Legionella pneumophila serogroup 1; L pneumophila serogroups 1 and 3 and several new Legionella species were isolated from the potable water system at the hotel. Following hyperchlorination of the potable water system, no further cases of LD in hotel visitors have been identified to date.