This study aims at describing smoking behavior and cognition for smoking cessation among Japanese men after the diagnosis of cancer. Subjects were 144 patients with head and neck cancer (oral cavity, pharynx and larynx without requirement of total laryngectomy) and 104 patients with stomach cancer who were current or ex-smokers at time of diagnosis. A self-administered questionnaire was mailed at least 1.5 years alter diagnosis. Response was by mail and 72% (248/344) of completed questionnaires were returned. Among 164 patients who were smokers at the time of diagnosis, 59(36%) reported that they continued to smoke after the diagnosis of cancer. Stomach cancer patients (53%) had significantly higher (p < 0.01) continuance rate of smoking than head and neck cancer patients (24%), and patients in fifties (53%) had the highest continuance rate of smoking in the study participants. Among 105 patients who were abstinent, 83(79%) had stopped smoking within 6 months after the diagnosis of cancer. Interest in smoking cessation among the current smokers was high (83%), and they preferred a smoking cessation class with multiple participants to "person to person" counseling provided by health care practitioners.