Among the risk factors that affect the occurrence of an illness or accident on board are human error, tiredness and complacency. A human error is common cause of marine accidents, and the cause of these accidents is mainly a chain human error. Tiredness also causes wrong judgment in managing and carrying out certain actions on board, and it also affects the health of seafarers and social aspect of their life. Complacency leads to a lack of motivation, discipline and concentration. In case of an illness or an accident on board, the injured person must be provided to injured person, i.e. certain medical-technical procedures carried out prior to the arrival of the physician and provision of professional healthcare. The aim of providing first aid on board is to remove the current danger to the life of the seafarer to whom is provided this assistance, or to prevent the deterioration of his health condition. The qualified ship's officer provides first aid on board. In this paper are analyzed the provision of first aid in cases of external and internal bleeding, shock, burns, electric shock, fractures, choking, drowning, poisoning and in cases of most common acute illnesses (sudden non-contagious and contagious diseases). There are also analyzed measures to prevent or minimize the risk of diseases and accidents on board, such as the use of personal protective equipment, vaccination, regular medical examinations, seafarers' training and education, proper organization of shipboard activities and the assessment of the risks of illness and maritime accidents. To seafarers will always threaten a certain risk of various illnesses and accidents, but these risks need to be managed to minimize their potential.