A method for the simultaneous detection and quantitation of amphetamine and methamphetamine in urine is described. Using solid-phase extraction, amphetamine, methamphetamine, and n-propylamphetamine (internal standard) are extracted from urine samples. Drugs in their free form are identified using gas chromatography/nitrogen-phosphorous detection (GC/NPD), whereas their heptafluorobutyric anhydride derivatives are detected by gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. Limits of detection for both amphetamine and methamphetamine are approximately 35 ng/mL. The procedure is simple, rapid, and suitable for a large number of specimens (25 or more).