A quantitative ELISA for the detection of IgG antibodies in response to the Cuban vaccine against the human leptospirosis (vax-SPIRAL) was applied to 930 volunteers'sera, 483 immunized with vax-SPIRAL and 447 with a vaccine against hepatitis B. Samples were taken before beginning the study, 21 days after the second dose and a year later. A high seroprevalence of antibodies to the vaccine serovars was observed before beginning the study. The initial value of the response doubled at 21 days of the second dose in 45 % of the individuals. There were markedly significant differences (p=0,000000) between both groups. A similar response to the three leptospiral serovars was found. After the year the levels of antibodies decreased; however, 23.1% of the individuals were able to duplicate their level of antibodies regarding the initial moment, and the significant difference with the group that received the vaccine against hepatitis B still existed. The application of this Cuban immunogen amomg the main risk groups was recommended.