The analysis of diseases and injuries in the workers on an American oil rig, operating in the Mediterranean Sea, was done in the period of one year, from 1 May 1996 to 1 May 1997. In total, 518 medical examinations of sick and injuried workers were conducted. At the first place in morbidity, there were injuries and poisonings (26.7% of all registered cases). Then followed musculo-skeletal (17.5%), respiratory (14.2%), gastrointestinal diseases (12.1%), mental disorders (10.3%), nervous system (9.2%), skin (6.5%), urogenital (2.9%) and circulatory system diseases (0.6%). Out of all cases, the hand and finger injuries (48.3%) were most frequent, followed by injuries of the leg (13.4%), eye (11.3%), head and neck (10.1%), arm (7.9%), foot (6.7%) and trunk (2.3%). To reduce the incidence of diseases and injuries, special attention should be paid to the workers' basic medical education, to protective measures and providing first aid at the work site.