Smoking is a major risk factor and main cause of many cancer types and death related cancer. It is the foremost cause of cancer mortality in the United States accounting for 98% of all tobacco related deaths. Smoking is the main preventable cause of lung cancer, it also affects the treatment. We investigated smoking status of our oncological patients. 372 patients information obtained from their files retrospectively. The 64.5% of patients were male (n=240), 35.5 % were female (n=132) and mean age was 60.9. 144 patients were nonsmoker (38.7%),148 patients were (39.8%) smoker and 80 were ex-smoker (21.5%). Mean consumed tobacco amount was 40.37 packet/year. 37.5% of the group was lung cancer, 18.6% of the group was breast cancer, 9.7% of the group was head and neck tumors. Only 9 (6.4%) patients from all lung cancer patients were nonsmoker, 60% were active smoker and 33.6% (n=47) were ex-smoker. Only 12 patients (33.3%) with head and neck cancer were nonsmoker, 22.2% were ex-smoker, 44.4 % were active smoker. 38.1% of gastric cancer patients were nonsmoker (n=8), 42.9 % were smoker and 19% were ex-smoker. Colorectal tumor group had a lower smoking ratio; 55.2% were nonsmoker and 10.3 % were ex-smoker. The least tobacco using ratio was at breast cancer group, 83.8 % of the breast cancer patients were nonsmoker. According to world health organisation, one third of cancer releated death is about basic behaviours as; high body mass index, poor fruits and vegetables in nutrition, poor physical activity and using cigarette and alcohol. We can change all of these situations. Because of strong relation between many kinds of cancer (not only lung cancer as common consideration) and tobacco, firstly we must conceive awareness about this relationship.