A simple, rapid and sensitive thin-layer chromatographic procedure has been developed for the identification and simultaneous determination of organophosphorus and carbamate insecticides. The RF values and suitable combinations of adsorbent, developing solvent and chromogenic spray are described in detail for eleven organophosphorus and seven carbamate insecticides. The procedures are suitable for determining these insecticides on sprayed surfaces and for the routine screening of food and agricultural products for tolerance limits. The convenient screening range is 0·1 to 20 µg on the chromatoplates.