Snakebite envenomation is considered a neglected public health problem in Brazil. Most of such accidents are attributed to different species of the genus Bothrops, of which Bothrops atrox is responsible for most cases. Snake venoms consist primarily of proteins, each of which performs a biological activity or acts synergetically to help snakes to survive by capturing and digesting prey and to defend themselves against attacks by predators. Studies have reported intraspecific and intrapopulational variability that depends on the age (ontogenetic variation), sex and size of the snake as well as geographic region. In the present study, variations in venom produced by the left and right glands of the same individual were assessed. Phospholipase A2 (PLA2) and coagulant activities and protein profiles were analyzed, and the immunogenic proteins in venom from each gland were titrated. In vitro results for venom from seven snakes of the species B. atrox (14 samples; one from each gland of seven snakes) revealed a statistically significant difference in PLA2 activity and coagulant activity between venom from the left and right glands in one snake. In addition, minor differences in protein profile were observed in SDS-PAGE and in the minimum concentration of proteins reactive to a polyclonal antiserum against B. atrox venom in a Dot-ELISA. The results therefore suggest that the same snake may be able to produce biochemically distinct venoms. However, the frequency with which these variations occur, their extent and whether they can cause clinical differences in vivo are not known.