A simple, convenient method is described for the detection in human urine of three major classes of drugs of abuse: amphetamines, barbiturates, and alkaloids. The drugs are adsorbed from urine by a column of non-ionic resin (Amberlite XAD-2), eluted with methanol, and chromatographed on a thin-layer silica gel plate. The drugs are made visible and identified by a series of procedures involving exposure to ultraviolet radiation, heat treatment, sequential spraying with group-specific reagents, and measurement of Rf values. Detection limits for 5-ml urine specimens are: 0.4 µg per ml for amphetamines and barbiturates, and 0.8 g per ml for alkaloids. The test requires 6 h to perform. One technologist can process 50 specimens per day.