Circular dichroism spectra were obtained for ten scorpion neurotoxins (representing five species of scorpion) in order to provide an understanding of their relative conformations in solution. Despite a high degree of amino acid sequence homology, the toxins clearly differ from each other in terms of CD-detectable structure. When superimposed, the CD spectra suggest that the toxins form a series of related conformational variants. Since the resemblances amongst the individual CD spectra can be correlated to degrees of sequence resemblance and pharmacological specificity, conformational balance could be an important factor in both toxin evolution and target recognition.