Abstract: Leptospirosis is an acute bacterial infection which affects humans and a wide range of animals this bacterial disease is caused by pathogenic members of the genus Leptospira. It is now known that this is only one of more than 200 pathogenic serovars distributed between 7 species and 23 serogroups worldwide. Commercial leptospiral vaccines rely on bacterins and inactivated whole cells. A major component of immunity resulting from whole cell vaccines is a humoral immune response resulted against the serovar specific carbohydrate antigen of leptospiral lipopolysaccharide. Cross protection against many of the 250 serovars of pathogenic Leptospira species is lacking though the immunity generated is readily demonstrable. Hence there is an urgent need for development of an improved leptospiral vaccine. Variations in the carbohydrate side chains of LPS are responsible for the antigenic diversity observed among Leptospiral serovars. The present study was undertaken to develop a recombinant fusion protein from Leptospira as antigen by the following processes. Identification and purification of gene encoding the leptospiral outer membrane OMPL1 by PCR. Cloning and expression of the OMPL1 gene in a suitable vector system. Purification and characterization of the expressed recombinant leptospiral outer membrane protein OMPL1. Standardization of recombinant antigen based diagnostic study.