Ethylenethiourea (ETU), a possible human carcinogen and an antithyroid compound, is the main degradation product of the fungicide, maneb, which is widely used in agriculture. In this study, a rapid and accurate method for the determination of maneb and ETU in various fruit juices (tomato, grape and apple) was developed requiring minimal clean-up of sample extract, no derivatization prior to injection and no specialized LC detectors. Samples were cleaned up using silica and octadecylsilica (C-18) cartridges before injection into liquid chromatography (LC) with diode-array detection (DAD). Recoveries ranged between 90 and 101% with relative standard deviations from 0.7 to 3.8%. The limits of determination of maneb and ETU were 0.1 and 0.01 mg 1(-1), respectively. The proposed method was used to monitor the presence of maneb and ETU in commercial samples taken from different markets of Istanbul, Turkey. Maneb was found in one tomato juice sample at a concentration of 0.45 mg 1(-1) but ETU was below the LOQ. Two tomato juices had no detectable maneb residue but contained ETU at levels of 0.08 and 0.11 mg 1(-1).