Basic organic drugs were extracted into ethanol from urine saturated with potassium carbonate. Drugs in this concentrate were purified by extraction into ether at pH 8.5. The ether extract was evaporated and applied to several thin-layer chromatograms. Functional-group detection was used in qualitative and semiquantitative analysis of the developed chromatograms by spraying the plates sequentially with several group-specific reagents. This simple, sensitive, and inexpensive procedure permits simultaneous analysis of many samples. It is well suited for detection of drug abuse.