Leptospirosis is a zoonosis that affects animal production and has impact a major health. While it is true, man is an accidental host [1] activities such as mining, agriculture, among others, pose a significant risk of contagion. In Colombia, serovar hardjo is the most important in cattle, followed by icterohaemorrhagie, grippotyphosa y canicola [2]. The purpose of this review is to show the practical importance of the classification of Leptospira in serovars at the time of diagnosis in animals and human patients.