Leptospirosis is a zoonotic disease distributed worldwide. It has now been identified as one of the emerging infectious diseases. The genomic sequences of Leptospira species have helped to identify the genetic diversity of hemolysins among different pathogenic and saprophytic Leptospira species. The phylogenetic analysis reveals that hemolysin SphH, a pore-forming protein on various mammalian cells in pathogenic Leptospira, does not show significant similarity to hemolysins in saprophytic Leptospira biflexa. The Leptospira interrogans hemolysin gene also does not show significant similarity to L. biflexa and Leptospira borgpetersenii. The genetic diversity among hemolysin genes in Leptospira suggests that the gain of more hemolysin genes during the course of their evolution may have contributed to their virulence.