In this paper it is described the characterization of the bovine mastitis in ten representative dairy cattle farms at Savannah of Bogotá, focusing in the study of the problem during two years with bimonthly visits. They were performed different types of field tests and laboratory test: general management of the farm, production records, the CMT, bacteriological cultures in Blood Agar, Mac Conkey Agar Sabouraud Agar, and Somatic Cell Count. These tests were performed in 644 cows and 2576 quarters with bimonthly visits, this gave a total of 7866 observations in cows and 31464 observations in quarters during the whole study. Complementary to the study, a weekly following was done during three months, to a group of 30 cows in three farms with milking by hand to determine the effect of the infection in the production of milk by quarters, using a bucket designed by the author. The results suggest a greater effect of the infection in the farms with mechanical milking where it was found a 61,2% of infection in cows, 30% of subclinical infection in quarters and a 4,7% of clinical infections in quarters. In the farms with milking by hand the infection was 48% in cows, 23.6% in quarters and a 3.6% of clinical mastitis cases. It was found a correlation of 91% between the CMT and the Somatic Cell Count, this agrees with the results of the other investigators. Turning to the different isolated microorganisms, it was found as prevailing Streptococcus agalactiae in the milking by hand and Staphylococcus aureus in the mechanical milking, and it was discarded the possibility of finding coliform microorganisms as a mastitis causative during the study. Refering to the effect in the production, they were registered losses up to five litres daily per affected cow, taking as indicator the CMT and the milk weigh. Also, it could be defined a decrease in the production by quarter of: 0.42, 0.90, 1.47, and 2.4 litres when the CMT readings (traces, 1,2,3,) were referred and was being used the bucket designed for this study. It was ...