The University National Oceanographic System operates a fleet of vessels to carry out its scientific projects. Illnesses and injuries at sea are handled by first responders aboard the vessels in consultation with land-based physicians at a telecommunications response center in the United States. During the period 1985 to 1987, 122 cases among regular and scientific crew required medical consultation by telecommunications. Of these, 31% were injuries, 34% were medical cases (infected), 12% were sexually transmitted diseases, and 23% were medical cases (noninfected). Evacuation from the vessel, vessel diversion, or repatriation of the patient was required for 20% of all cases; of these, 48% were for injuries, 36% for noninfected medical illnesses, and 16% for infected medical cases. Rates of illness and injury were calculated using the crew days at sea as a denominator.