Hair proteins have been analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis using a simplified method without S-carboxymethylation, protein fractionation and lyophilization. The molecular weights of the proteins have been determined and human, rat, guinea pig, rabbit, gerbil, cow and sheep hair compared. These molecular weight values are consistent with those obtained using physical methods as compared to anomalously high values previously reported following electrophoresis of S-carboxymethylated hair proteins. Additional high molecular weight proteins, possibly of a dimeric nature, have also been detected.