Brucellosis and Leptospirosis are diseases that affect humans beings and domestic animals worldwide. In relation to the diagnosis of these two diseases, must take care, because it can bring a serious economic problem to ranchers, since animals with brucellosis, should be sacrificed, while animals infected with Leptospira can be treated. The objective of this study was to verify if exist seropositive cattle for leptospirosis, among seropositives for brucellosis in official tests. Were collected 214 blood serum samples from adult cattle of the region of Uberlândia, Minas Gerais State of Brazil, wich were subjected to the diagnostic screening test for brucellosis (Rose Bengal test) conducted at the Laboratory of Infectious Diseases, Faculty of Veterinary Medicine, Federal University of Uberlândia. Positive samples in Rose Bengal test, were referred to the confirmatory test 2-mercaptoethanol (2-ME) according to PNCEBT (Governamental Program) and microscopic agglutination test (MAT), to detect antibodies anti-Leptospira spp. Of the 214 samples taken from cattle of the region of Uberlândia, 52 (24.29%) were reactive in the screening Rose Bengal test, and of these, 33 (63.46%) were confirmed seropositives and 19 (36.53%) were negative in confirmatory diagnosis test of brucellosis, 2- Mercaphtoethanol (2-ME). Considering the samples confirmed by 2ME, 13 (39.39%) of these also reacted to the test of SAM. Thus, of the 52 positive cattle in the Rose Bengal test, 13 (25%) presented both, brucellosis and leptospirosis. Of the total samples, 162 (75.70%) showed negative results in Rose Bengal test, and among these, 109 (67.28%) were positive for one or more Leptospira interrogans serovars and 53 (32.71%) negative for leptospirosis. Those results, may be the from of a double infection, or vaccine reactions and even non specific reactions. This project was financially supported by CNPq and Fapemig, to which we are grateful. We would also like to thank the veterinary doctors who donated the samples to this project.