Objective: Cigarette smoking is one of the primary causes of cancer. Tobacco exposure affects many parameters such as prognosis, response to treatment, and quality of life after a cancer diagnosis. We aimed to assess the association between smoking status with demographical and clinical characteristics of patients with malignancy who were referred to the Nuclear Medicine Department. Material and Methods: A total of 440 (59.8% males; median age 62 years) patients diagnosed with malignancy who applied to the nuclear medicine department between December 2018 and May 2019 were assessed. The smoking behavior of patients was examined according to cancer diagnosis, age, gender, and education level. The factors that may affect quitting smoking after the cancer diagnosis were evaluated. Results: Thirty-eight percent of patients were never smoked, 51.4% were former smokers, and 10.7% were current smokers. Smoking history in men and women was present at the rate of 87.8% and 23.7%, respectively. Breast and gynecological cancers were more common in never-smoker females (p<0.001). The lung cancer rate was higher in men who smoked (p<0.05), gastrointestinal system cancer was higher in never-smoker men (p<0.05). Age, male gender, education status that high school and above, and a lung cancer diagnosis were found to be significantly higher in patients with a smoking history (p<0.05). Those who were <65 years old and had a smoking history of >30 pack-years had a risk for continuing smoking (p<0.05). Conclusion: Young age and more cigarette pack-years are factors that negatively affect quitting smoking. Smoking status is associated with the type of cancer in both genders.