An understanding of the cross-neutralisation of snake venoms by antibodies is important for snake antivenom development. We investigated the cross-neutralisation of brown snake (Pseudonaja textilis) venom, taipan (Oxyuranus scutellatus) venom and death adder (Acanthophis antarcticus) with commercial antivenoms and monovalent anti-snake IgG, using enzyme immunoassays, in vitro clotting and neurotoxicity assays. Each commercial antivenom bound all three venoms, and neutralised clotting activity of brown snake and taipan venoms and neurotoxicity of death adder venom. The 'in-house' monovalent anti-snake venom IgG raised against procoagulant brown snake and taipan venoms, did not neutralise the neurotoxic effects of death adder venom. However, they did cross-neutralise the procoagulant effects of both procoagulant venoms. This supports the idea of developing antivenoms against groups of snake toxins rather than individual snake venoms. Crown Copyright � 2009.