The metabolism of drugs and chemical carcinogens involves a variety of isoenzymes such as members of the Cytochrome P450 (CYP) and Glutathione S-transferase (GSTs) families, with polymorphisms described in these genes appearing to be responsible for differences in individual susceptibility to cancer Furthermore, the cytochrome P450 family (CYPs) and the glutathione S-transferase (GSTs) enzymes also play an important role in the metabolism of environmental carcinogens and of estrogen and can affect various cancer types. In this study we examine the role of the genes CYP1A1 and GSTM1, in different cancer types in Turkey population. The aim of our work was to evaluate the association between CYP1A1 and GSTM1 genetic polymorphisms and activities of genes indicative for susceptibility to various cancer types in Turkey population. The polymorphic inheritance of human drug-metabolizing enzymes, such as those encoded by the GST and CYP systems, has been implicated in all the cancer risk and prognostic. The study population consisted of 80 different incident cancer cases and 100 healthy controls. Genotyping analyses were performed by PCR based methods. In conclusion, in our population GSTM1 was associated with breast, gastric, endometrium, testis, parotis, lymph node, pancreas, tyroid, and lung cancer risk in Turk population. The analysis of patients by histological types of different cancer showed no association between histopathologic types of cancer and CYP1A1 gene polymorphism (p=0.6). Genetic researches using specific biomarkers are expected to be helpful in evaluation the risks for every cancer type.