Cross-reactivity with Diagnostic Products Corporation (DPC) amphetamine and methamphetamine radioimmunoassay (RIA) reagents was determined for amphetamine, methamphetamine, and a number of amphetamine analogs. Concentrations from 100 to 100, 000 ng/mL were assayed. 3, 4-Methylenedioxyamphetamine (MDA) and 3, 4-methylenedioxymethamphetmaine (MDMA) showed significant cross-reactivity for the amphetamine and methamphetamine reagents respectively. 4-Hydroxymethamphetamine, 3, 4-methylenedioxyethylamphetamine (MDEA), and N, N-dimethyl-MDA also showed significant cross-reactivity with the methamphetamine reagents, but less than MDMA. None of the other analogs showed a positive result with the amphetamine or methamphetamine reagents at even the highest concentration, although several did show measurable cross-reactivity. The l isomers of amphetamine and methamphetamine showed substantially less cross-reactivity than the d forms to which the respective antibody systems are targeted. © 1990 Oxford University Press.