A B S T R A C TIllnesses and accidents occur on board seagoing vessels. In these cases, lacking medical or paramedical personnel, the ship's captain or an officer delegated by him provides medical care and in general asks for medical advice by means of telecommunication systems. The situation is in general different on passenger ships, on board of which are doctors or paramedical personnel. Telemedicine services for ships without medical facilities are provided by the Telemedical Assistance Services (TMAS). The captain is always responsible for medical care and final decisions regarding health of seafarers. Full responsibility for the diagnosis and prescription of treatments belongs to the doctor on board or to the TMAS physician. The physician on the ship or at TMAS should protect the privacy of patients. The telemedicine services and in particular the doctor-patient relationship on vessels present ethical and legal issues that are not the same as those experienced ashore. These issues are discussed and some possible solutions to improve patient-physician relationships are suggested.