60 cases of leptospiroses were diagnosed in Polynesia by blood culture and immunological test. Fever and pains are prevailing signs. Among 3 patients, presence of leptospires is revealed on the 43th, 54th and 90th days. The following serogroups are found: Icterohaemorrhagiae 69.7%, Canicola 13%, Pomona 4%, Australis 2%. 85% of the patients come from Tahiti and 15% from "Sousle-Vent" Islands and Tuamotou. Walking bare foot on wet ground in areas where numerous rodents are found is a source of contamination. The procedure of blood cultures plays a prominent part.