Frequently, leptospirosis is related to reproductive problems in livestock, such as abortion, increased embryonic mortality and stillbirths. Unfortunately, there are few reports addressing the prevalence of the disease in cattle in the North of Mato Grosso State (MT), Brazil. The aim of the present study was to determine the presence of anti-Leptospira spp. antibodies in cattle in the municipalities of Nova Guarita and Nova Santa Helena, MT. Nine hundred and eighty blood samples were taken from cows aged ?24 months from 49 farms slaughtered in Sinop, MT. Microscopic Agglutination Test was used for the detection of anti-Leptospira spp. antibodies. The animal prevalence was 17.9% (95% CI = 15.6-20.5%). The prevalence observed in the municipalities Nova Guarita and Nova Santa Helena was 13.4% (95% CI = 12.8-14.1%) and 23.2% (95% CI = 22.0-24.3%), respectively. The herd prevalence was 83.6% (95% CI = 79.4-87.8%). The most frequent serovar was Wolffi (47.7%), followed by Hardjo (16.1%), Hardjo - Bolivia sample (11.0%), Australis (7.4%), Grippotyphosa (4.6%), Pomona (3.4%), Batavie (3.4%), Autumnalis (1.7%), Icterohaemorrhagiae (1.7%), Hebdomadis (1.1%), Hardjo-bovis (1.1%), and Castellonis (0.5%). Infection by Leptospira spp. is endemic in both municipalities, reinforcing the need for new epidemiological studies to subsidize the control of the disease in Mato Grosso
