The detection of many synthetic chemicals used in industry that may pose a genetic hazard in our environment is of great concern at present. In this respect, administrative authorities has great concern to regulate and to evaluate the chemical hazard to environment and human health. The clastogenicity of 28 synthetic chemicals was evaluated in Chinese hamster lung fibroblast cells in vitro. Glycidylacrylate which is one of the most cytotoxic chemical among 28 chemicals tested revealed clastogenicity in the range of 0.31-1.25 $mu extrm{g}$/$mell$ both in the presence and absence of metabolic activation system. Neopentyl glycol (340-1360 $mu extrm{g}$/$mell$) also revealed weak positive result both in the presence and absence of metabolic activation system. Cyanoguanidine (/$420.5-841 $mu extrm{g}$mell$</TEX>) and N-butylchloride ($231.5-926 $mu extrm{g}$/mell$</TEX>) revealed weak positive result only in the absence of S-9 metabolic activation system. Nevertheless total aberration percentages of N-butylchloride in the presence of metabolic activation system, and 3,4＇-dichlorobenztrifluoride in the absence of S-9 metabolic activation revealed above 5% aberration, there is no statistical significance. From the results of chromosomal aberration assay with 28 synthetic chemicals in Chinese hamster lung cells, glycidylacrylate (CAS No. 106-90-0), neopentyl glycol (CAS No. 126-30-7), N-butyl chloride (CAS No. 109-69-3) and cyanoguanidine (CAS No. 461-58-5) revealed positive clastogenic results in this study.