The aim of this study was to evaluate in the laboratory different isolates and concentrations of conidia of Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1883 and Beauveria bassiana (Balsamo) Vuillemim, 1912 for control of the cattle tick. The conidial suspensions were prepared from fungi grown in rice medium in polypropylene bags. The tests were performed by immersion of engorged females collected from animals not treated with acaricides. The experimental design was completely randomized with 20 treatments and 5 repetitions, each consisting of 5 females. The mortality rate caused by the fungus M. anisopliae ranged from 92 to 100%, while for B. bassiana it was 44 to 100%; mortality was greater at concentrations of 10(8) and 10(9) conidia mL-1 suspension. The isolates B. bassiana Fitossan 1 and M. anisopliae PL 43 (both at 10(9) conidia mL-1) and Fitossan 4 (10(8) conidia mL-1) within 14 days of treatment killed 100%, 92% and 88% of the engorged females, respectively. In general there was no difference in the weight of eggs from females treated with the same isolate at concentrations of 10(7), 10(8) and 10(9) conidia mL-1, although isolates of M. anisopliae had lower weight. The efficiency of control ranged from 0% (control with water) to 31.30% (M. anisopliae Fitossan 4, 10(8) conidia mL-1).