Bowens Disease (BD), squamous cell carcinoma in situ, is prevalent in elderly patients and occurs in sun-exposed areas. Historically, BD has been treated by various modalities including Mohs surgery and cryosurgery. Radiotherapy (RT) has been reserved for those patients who refuse surgery, have large or multiple skin lesions, or when surgery could result in a poor cosmetic and functional outcome. Limited data exists on RT for BD, especially as an alternative to amputation in patients with digit lesions. At our institution, a multidisciplinary team of dermatologists, surgeons, and oncologists evaluate each patient and reach a consensus as to whether surgery or RT will result in optimal function, cosmesis, and cure. Here we report on the efficacy and toxicity of RT in patients with Bowens Disease. After obtaining consent through the IRB, the charts of 44 patients with 70 lesions treated between 1993 and 2003 were reviewed. Median age was 76 years (range 46–95); 60% were female. 10/44 (23%) patients had more than one lesion treated. Sites treated included the face/head (34%), lower extremities (33%), digits (17%), trunk (9%), and other sites (7%). Median lesion size was 25 mm (range 4–66). Eleven lesions were treated with surgery or cryotherapy prior to RT. 10/12 digit lesions were circumferential and RT was determined to be the only alternative to amputation. While many patients were referred for RT based upon lesion location and/or poor surgical risk, 31% were referred for RT based upon patient preference or physician opinion that RT would be more efficacious than surgery. The median dose prescribed was 49 Gy (range 25–66 Gy), 2.5 Gy fractions (range 2–4 Gy), 5 times per week. Most lesions received 6 or 9 MeV electrons with a 0.5–1cm bolus prescribed to the skin surface. Median Time-dose-fractionation (TDF) value was 93 (range 46–148). Digit lesions were immersed in a water bath and treated with photons with dose prescribed to the midplane. With a median follow-up of 16.7 months (range 0.5–101 months), 3/71 lesions have recurred in the shin and scalp (2 lesions) after 30 and 57 months, respectively, for a crude rate of local control of 96%, and an actuarial rate of control of 92% at 3 years. The patient with two scalp lesions was salvaged with Mohs surgery. The second patient had six lower extremity lesions treated; one recurred requiring a wide local excision and a skin graft. Both patients have no evidence of disease. Thus, the ultimate rate of local control for the entire series was 100%. Acute toxicity consisted of minimal erythema (63%), dry desquamation (17%), moist desquamation (11%), and skin ulceration (4%). Late toxicity occurred in 11% of patients including telangiectasia (3 lesions), hyperpigmentation (2 lesions), and ulcers which required skin grafts in a patient with two lower extremity lesions. Acute toxicity or ulceration failed to predict for late ulceration. All digit lesions were without evidence of disease at last follow-up. Median follow-up for patients with digit lesions was 21 months (range 0.5–43 months). Moist desquamation (2 lesions) and ulceration (3 lesions) were observed without any long-term sequelae. Full range of motion and strength were maintained except for one patient who developed mild weakness and numbness in her fingertips which did not alter her daily activities. Dose per fraction, total dose, lesion size, TDF, or other treatment-related variables failed to predict outcomes or toxicity. Although continued follow-up of these patients is needed, our results demonstrate high rates of tumor control following RT in the treatment of BD. RT is a primary treatment option, especially when resection could result in a functional loss or in cases of poor surgical risk. This was especially true in the treatment of digits. This is the first study to show that RT can be used as an alternative to amputation to preserve normal digit function. Through a multidisciplinary sharing of knowledge and specific patient selection criteria, treatment of BD with surgery or RT should continue to result in a very high cure rate with minimal toxicity