Between 1975 and 1992 2468 patients (94.5% male, 5.5% female) have been treated for thromboangiitis obliterans (TAO). Mean age was 43 ± 10 years (range 23-80 years) at the time of diagnosis. Whereas only 8% of patients were older than 40 years of age in 1975, this figure has increased to 44% in 1992; 25% of male and 64% of female cases were older than 40 years of age. At the time of admission, 78.2% had rest pain, 58% had intermittent claudication, 17.6% had superficial thrombophlebitis, 10.5% had Raynaud's phenomenon, and 68.9% had ischemic ulcers. The study period has been divided into early (1975-1983) and late periods (1984-1992). In the late period, we have noted an increase in the upper extremity involvement rate (47.5%) and an increase in large artery involvement rate of the leg (40.1%). In both periods, the majority (58%) of the patients with large artery involvement were older than 40 years of age. Sympathectomy, amputation, revascularization, and medical therapy were proven to be mostly ineffective. Of the patients who stopped smoking, 5.7% had subsequent amputations whereas 46% of patients that continued to smoke had single/multiple amputations. We have demonstrated that TAO is no longer a sole pathology of the small/medium-sized arteries affecting young male smokers' lower extremities.