"Seafarer" means person employed with any job on board a ship offshore, whether publicly or privately, excluding ships of war. Day by day a seafarer is forced to confront a reality in constant motion and live in environments that require awkward movements, and restricting the normal mobility of the person. In order to verify the frequency of herniated discs in this particular category of workers, given the recent introduction of INAIL tabulated diseases, a study was conducted on a sample of seafarers. Data analysis showed that 48.3% of the seafarers of the sample has herniated lumbar disc, and 34.5% of these duties in the deck, and 65.5% of the machine. The study of sample, varied as to age and task being performed, supports the assertion that the individual risk factors, especially age and obesity, are not strongly implicated in the genesis of disk herniation suffered by seafarers while the work factors (vibrations) play a more significant role in the onset of this disease. This consideration is part of a context, that of legal medical evaluation and in particular the causal relationship, which currently seems rather lacking in terms of literature and scientific production.