ABSTRACT
The aim of this study was characterize the positivity of the bovine leukosis virus in the Microregion of the Serra de Botucatu. Sera from 1193 bovine from 65 properties of the Microregion of the Serra de Botucatu were evaluated throught ELISA test. All the evaluated animals were adult and 16 of them only were male; 85.5 percent were crossbred, 6.45 percent Nellore and 8 percent dutch. Of the analyzed samples, 618 sera had resulted positive to the test. In only one flock it was not found seroreagents animals, the regional positivity was 52 percent (the seropositivity in the properties varied of 10 percent to 67 percent), the higher the percentage of positivity was in the animals of the dutch race (94.7 percent), followed for the crossbred (43.7 percent). The high percentage of positivity of the disease in our region is distinguished.