A seroepidemiological study was conducted to assess the seroprevalence of hepatitis A, B and C markers in 285 males (mean age: 24.4+/-4.4 years) aboard a Greek warship. Two hundred and sixty three serum samples were tested. None was found to be positive for HAV antibodies, three persons (1.1%) were positive for HBsAg, four persons (1.5%) were positive for anti-HBc and one person (0.4%) was positive for anti-HCV. Forty-five persons (17.1%) had developed titles anti-HBs > 10 IU/L. The establishment of a vaccination policy against hepatitis A among warship personnel is strongly recommended.