Background: Basal cell carcinoma (BCC) is the most common cutaneous malignancy. UV light is an important risk factor for BCC, as well as X-ray and other ionizing radiations. The aim of this study was evaluation and risk factor assessment of BCC cases referred to Razi hospital tumor clinic. Methods: Patients referred from general clinics with skin biopsies consistent with Basal Cell Carcinoma were enrolled. A questionnaire including epidemiologic data, risk factor exposure and specification of skin lesions was completed for each patient. Results: From October 2005 to October 2006, a total of 476 patients with cutaneous malignancy referred to Tumor clinic of Razi hospital. Of them, 367 patients had BCC. 215 were male (58%) and 152 were female (42%). Mean age of patients was 62 (±12.7) and 62 (±13.4) years for men and women, respectively. The most common risk factors for BCC were radiotherapy and chronic sun exposure. The most common tumor sites were scalp, nose and ears. Of different clinico-pathologic types, noduloulcerative type was the most common. Conclusion: It seems that radiotherapy is an important risk factor in Iranian BCC patients and it is useful to have a screening program for case finding and treating patients in early stages.