Polyclonal rabbit antibodies raised against a non-toxic protein (TsNTxP) purified from the toxic fraction of the crude venom of Tityus serrulatus can neutralize the effects of the venom. The antigenic specificities of anti-TsNTxP were compared by an indirect enzyme-linked immunosorbent assay using TsNTxP, TstFG50 (toxic fraction of venom that represents most of the toxicity of the crude venom), and crude venoms from T. serrulatus, T. bahiensis, T. cambridgei, T. stigmurus, Androctonus australis Hector and Centruroides sculpturatus to coat microtitration plates. The anti-TsNTxP antibodies had a comparable high cross-reactivity with the toxic fraction and crude venom of T. serrulatus, moderate binding capacity for T. bahiensis, T. cambridgei, T. stigmurus and were unable to recognize the venoms of A. australis Hector and C. sculpturatus. Quantities of venom equivalent to 20 LD50 were effectively neutralized by 1 ml of the anti-TsNTxP serum. This result shows that this protein may be of interest in the production of antivenoms for clinical use.