This manuscript describes the general biochemical properties and immunological characteristics of Peruvian spider Loxosceles laeta venom (PLlv), which is responsible for the largest number of accidents involving venomous animals in Peru. In this work, we observed that the venom of this spider is more lethal to mice when compared with L. laeta venom from Brazil (BLlv). The LD50 of PLlv was 1.213mg/kg when the venom was intradermally injected. The venom displayed sphingomyelinase activity and produced dermonecrotic, hemorrhagic and edema effects in rabbits. 2-D SDS-PAGE separation of the soluble venoms resulted in a protein profile ranging from 20 to 205kDa. Anti-PLlv and anti-BLlv sera produced in rabbits and assayed by ELISA showed that rabbit antibodies cross-reacted with PLlv and BLlv and also with other Brazilian Loxosceles venoms. Western blotting analysis showed that bands corresponding to 25-35kDa are the proteins best recognized in every Loxosceles spp venoms analyzed. The immunized rabbits displayed protective effect after challenge with PLlv and BLlv. Invitro assays with horse anti-loxoscelic antivenoms produced in Brazil and Peru demonstrated that these commercial antivenoms were efficient to inhibit the sphingomyelinase activity of PLlv and BLlv.