Loxoscelism or brown spider envenomation is the most important form of araneism in some countries and constitutes the third cause of accidents by venomous animals in Brazil. The treatment of Loxosceles bites is still controversial, with a variety of interventions proposed and tried, such as antivenom. The majority of clinical studies demonstrate a significant delay between a spider's bite and presentation for treatment, and this delay is thought to lead to an ineffective administration of a specific antivenom. Even in Brazil, where the antivenom therapy has been indicated more frequently than in other countries, there are still doubts about its real capacity to neutralize local and systemic effects of the envenomation and the ideal period for its administration. Thus, various studies in animal models have tried to correlate the time of envenomation with the application of the antivenom and the permanence of the venom in circulation or in dermonecrotic lesions. The purpose of this study was to evaluate the use of antivenom in loxoscelism treatment and to systematize the results of studies in animals and humans available in the last 30 years, making possible a more critical analysis of the efficacy of the antivenom or its therapeutic value in bites by spiders of the genus Loxosceles.