While the trend of cigarette consumption in some developed countries is on the decline, it has been noted that in many developing countries, smoking is on the increase. Compared to developed countries, there are more male smokers than female smokers in these countries. The aim of this study was to investigate the prevalence and characteristics of the smoking habit in patients having lung cancer (LC) and to find out if there is any relationship with the smoking habit and the pathological diagnosis in our patient population. This hospital-based study was carried out between 1990 and 1996 in two major medical centres. LC was diagnosed in 1046 patients, 966 of whom were males (93%), and the remaining 80 (7%) of whom were females. Upon diagnosing the male patients, it was noted that 83% were current smokers (CS), 12% were ex-smokers (ES defined as abstinence from smoking at least for 1 year), and the remaining 5% were non-smokers (NS). In the female population the findings were as follows, 16% were CS; 8% were ES, and 76% were NS. The period of abstinence in the ES was 10 years or less in 77% of the patients. Among the male patients, squamous cell carcinoma was the most common tumor type seen in the CS group (46%) while adenocarcinoma (45%) was the most commonly seen tumor in the NS group. On the other hand, in the females, CS, the most commonly noted tumor types were small cell (54%), and adenocarcinoma (39%) was most frequently found in NS group. These results indicate that ES patients having LC in this study was quite low. On the other hand, in contrast to the findings of many other studies, from developed countries, the majority of male LC patients were in the CS group, however the majority of female LC patients were in the NS group. This smoking habit data obtained from our LC patients suggests that, similar to underdeveloped or developing countries, smoking cessation rates are very low in men during the past decade, and interestingly smoking rates may increase in women in the near future in our country. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.