Familial Mediterranean Fever (FMF), characterized by recurrent polyserositis, is an autosomal recessive disease involving essentially Mediterranean populations. We report the case of a 30-year-old Tunisian military patient complaining of fever and chest pain recurring on board a Navy military vessel, due to side-changing pleural effusion. On landing, a marked improvement of symptoms was noticed. Gene testing was performed when the diagnostic survey ruled out common etiologies, revealing a homozygous mutation of the FMF gene type M680l/M680l. The prescription of colchicine and the exemption from boarding led to the resolution of the symptoms with no recurrence of pleural effusion. Therefore, the diagnosis of FMF should be considered in a context of a recurrent pleural effusion in the youth, with a negative etiological assessment, notably in an ethnic group at risk. Thus, early diagnosis and adequate treatment may prevent the development of secondary amyloidosis, a serious complication of FMF.