A new isolate of Metarhizium flavoviride Gams and Rozsypal (Hyphomycetes) (CG 423) found in Northeast Brazil infecting Schistocerca pallens (Thunberg) was identified using arbitrarily primed PCR. Cluster analysis of DNA markers revealed a high level of homogeneity (>83% similarity) among the Brazilian (CG 423) and two other M. flavoviride isolates from Nigeria (CG 366 = IMI 330189) and Australia (CG 291). However, M. flavoviride isolates were very distinct when compared with two isolates of Metarhizium anisopliae (Metschnikoff) Sorokin (6.4% similarity). Bioassays showed that strain CG 423 is as virulent as other isolates of M. flavoviride (CG 291, CG 366), M. anisopliae (CG 087), and Beauveria bassiana (Balsamo) Vuillemin (CG 425) against the grasshopper Rhammatocerus schistocercoides (Rehn) (Orthoptera: Acrididae), an important pest in Central Brazil. However, the Brazilian isolate of M. flavoviride (CG 423) is more virulent than the Brazilian isolate of B. bassiana (CG 250). Because conidia used in bioassays were formulated in soybean oil containing 5% kerosene, the effect of the kerosene present in the oil formulation was tested. Kerosene (0–10%) did not affect the virulence (P > 0.3) of M. flavoviride against R. schistocercoides. The native isolate of M. flavoviride (CG 423) is now being developed as a mycoinsecticide against grasshoppers in Brazil.