Clinical samples from 293 patients with suspicion of leptospirosis were studied for the microbiologic confirmation of these events, in October-December 2005, when there were 2 outbreaks in humans, in Cuba. Sera samples of patients in acute phase and during convalescence, as well as hemocultures performed before the beginning of the antibiotic therapy, were analyzed. Conventional techniques (passive hemagglutination test and serogroups hemagglutination), and advanced or fast diagnosis techniques (Lepto tek Dri-Dot, Lepto-Cuba, Latex-India, Lepto tek Lateral Flow) were used for serologic diagnosis. In outbreak 1, 26 % of the studied cases were confirmed by serological tests (22/84), and 25% (5/20) through hemocultures; whereas in outbreak 11, 48 of the 162 studied cases (30%) were serologically confirmed, and it was possible to obtain isolation of leptospires in 6 of the 27 processed cases (22%). The main serovariants found by serology were Canicola, Ballum, Icterohaemorrhagiae, and Pomona. The rapid diagnosis methods were useful screening tools in the most severe cases or at pediatric ages. The two epidemiologic events were caused by pathogenic leptospires infection, which contributed to the adoption of hygienic-sanitary measures in both provinces.