Because of its clinical polymorphism and the difficulties to made a bacteriological and/or serological diagnosis, leptospirosis is an affection always non-detected. Nevertheless it is daily met affection in French Polynesia. Based on a homogenous series of 120 observations gathered from 1984 to 1990, all of them bacteriologically and/or serologically confirmed, we studied the different clinical and evolutive features of that disease. Fever is present in 91.6 p.c., cephalgia in 79.16 p.c. and myalgia in 70.83 p.c. Admission was necessary once out of four times. The four syndromes we observed in Tahiti are: infections syndrome, meningeal syndrome (30 p.c.) associated to an hyperproteinic grade in the C.S.F. (40 p.c.) and a lymphocytic reaction (60 p.c.). Liver syndrome, with hepatalgia (58.33 p.c.) and pain at the mass motion of liver (65 p.c.), that is an important sign in the local context; jaundice (28.33 p.c.) on the presence of which we must not based a diagnosis of leptospirosis: Biological renal syndrome displayed by transitory renal insufficiency with proteinuria, hematuria and leucocyturia. Neurological complications are mainly of encephalitic manifestations (5.8 p.c.). Hemorrhagic syndrome is expressed in digestive hemorrhage (8.33 p.c.) epistaxis (6.66 p.c.) and hemoptysis (6.66 p.c.). Cardiovascular manifestations are expressed in collapsus in 5.83 of the cases. Pulmonary abnormalities are frequent: cough (26.66 p.c.) and non specific X Ray image (19.16 p.c.). All patients are treated by Penicillin G (10 to 20 millions per day) by parenteral route with enteral alternative for an average of 10 days. Recovery was fast (7 to 10 days). In 65.8 p.c., slower in 15 p.c. (15 to 20 days); failure at first stage was observed in 10 p.c. of the cases, and relapse at medium or long term occurred under treatment in 8 cases (6.66 p.c.). Three dead were deplored (mortality 2.5 p.c.).