To study the effects of serum p21 levels on the health of coal tar pitch(CTP) and coke oven volatiles (COV) workers recognized as the high risk population of pulmonary carcinoma, serum p21 levels among 24 cases of CTP workers, 25 cases of COV workers and 12 cases of normal control were detected with the method of Western Blotting. The results showed that the mean serum p21 level in exposed group was significantly higher than that in the normal control (366.8 vs 1270.7, P < 0.001). In the COV workers, serum p21 level in coke furnace workers was remarkably higher than that in the workers with other types of work. There were no differences for p21 among workers with different work years and between workers with or without smoking history. It indicates that CTP and COV can cause the p21 protein level increase in the occupational population.