Two chimpanzee mAbs specifically reacted with light chain of the botulinum neurotoxin A and neutralize the toxin in the mouse model. They can be used for emergency prophylaxis and treatment of either naturally acquired or terrorist associated botulism. Since the sequence of chimpanzee immune globulin is virtually identical to that of humans, the MAbs are not expected to have problems in repeated administration as equine antibodies. They can also be used for rapid diagnosis of botulinum neurotoxin A.