Cytochrome P450 1A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) metabolize tobacco-related carcinogens. To investigate the prevalence of CYP1A1 and GSTM1, and their association with increased risk of lung carcinoma in Chinese, allele-specific PCR and multiplex PCR technique were employed to identify the genotypes of CYP1A1 and GSTM1 in a case-control study of 106 lung carcinoma patients with histopathological diagnosis and 106 matched controls free of malignancy in Jiangsu Province, China. Logistic regression analysis was performed to calculate the odds ratio (OR) and 95% confidence intervals (CI). The results showed that individuals with GSTM1 null, and the combined GSTM1 null/CYP1A1 Ile/Val or GSTM1 null/CYP1A1 Val/Val had an elevated risk of lung carcinoma, with the OR, 1.92 (P=0.02; CI, 1.07-3.46), 3.27 (P=0.01; CI, 1.23-8.84) and 9.33 (P=0.04; CI, 1.01-217.42), respectively. Light smokers (<30 pack-years) carrying GSTM1 null genotype were shown to have the increased risk to lung carcinoma (OR=3.47; CI, 1.13-7.57). Our study suggested that the null GSTM1 genotype, independently or in combined with at least one Val allele of CYP1A1, might affect the genetic susceptibility for lung carcinoma in Chinese population.