Amphetamine and methamphetamine are extracted from 200 microL of urine into an organic solvent containing propylchloroformate. The amines immediately react to form propylcarbamate derivatives. The aqueous phase is removed, and a portion of the organic phase is analyzed by gas chromatography-mass spectrometry. Either the deuterated analogues or N-propylamphetamine internal standards give acceptable results. For day-to-day precision, coefficients of variation in the range of 6-10% are found. The method is linear to 10,000 ng/mL. Limits of quantitation and detection are 50 and 5 ng/mL, respectively, when using N-propylamphetamine as the internal standard. Extracts are stable at room temperature for at least 60 days. There is no interference from other amphetamine drugs.