Pulsed-field gel electrophoresis (PFGE) studies performed with leptospiral isolates led us to suspect the existence of a new serovar in the Grippotyphosa serogroup. The results obtained with reference serological techniques used in leptospiral identification, including cross-agglutination absorption and monoclonal antibody techniques, confirmed the existence of a new serovar exemplified by strain Dadas I. Four other isolates from different regions of the world were submitted for identification by PFGE and produced NotI restriction patterns similar to that of strain Dadas I. Our data demonstrate the power of PFGE for identifying leptospiral isolates. The name dadas is proposed for the new serovar.