Antisera to optical isomers of methamphetamine were produced in rabbits immunized with d-, dl- or l-N-(4-aminobutyl) methamphetamine conjugated to bovine serum albumin. The specificity of antibodies obtained was shown by cross-reaction studies with the optical isomers of methamphetamine. The results indicated that the antiserum to d- or l-methamphetamine was specific to d- or l-methamphetamine, respectively, although the antiserum to dl-methamphetamine recognized both d- and l-methamphetamine to almost the same degree.