From 1966 to 1991 91 cases of bites due to mygalomorph spiders were recorded at the Hospital Vital Brazil, Instituto Butantan, São Paulo, Brazil, representing less than 1% of all spider bites. The diagnosis was confirmed by positive identification of the spider involved. Envenoming is generally mild, the main symptom is local pain, and there is minor oedema and erythema. The data confirm the assumption that these nonaggressive spiders pose no health problem.