e19505 Background: Primary cutaneous lymphomas occur in 0.5 to 1 per 100,000 people every year in developed countries. Less than 1,000 cases of Mycosis Fungoides are diagnosed each year in the United States, with approximately 3 cases per 1,000,000 per year. Cutaneous T-cell lymphomas are responsive to radiation therapy, and local radiation therapy, total skin electron beam therapy, phototherapy (with UVB or PUVA), chemotherapy agents (nitrogen mustards, BCNU), retinoids, and steroids have all been used with varying degrees of success. Methods: This is a retrospective review of all cases of histology-proven cutaneous T-cell lymphoma treated with single-fraction radiation therapy at Northwestern Memorial Hospital in the Department of Radiation Oncology since 1990. We looked at response to treatment and local control. We reviewed the charts of 67 patients with cutaneous T-cell lymphoma, of which 40 patients and a total of 130 sites of disease received single-fraction radiation therapy and had available follow-up data. Results: Of the 130 lesions receiving a single-fraction of radiation, 86 (66%) received 800cGy in 1 fraction and 38 (29%) received 700cGy. 4 patients (3%) received 750cGy, 1 (<1%) received 550cGy and 1 (<1%) received 500cGy. Patients were treated with electron energies ranging from 6–18 MeV or photon energies ranging from 4–10 MV. Out of 130 lesions, 119 (92%) achieved a complete response (CR) to single-fraction radiation and 11 (8%) achieved a partial response (PR). There were 2 sites of relapse out of 130 treated sites, involving 2 patients. The median follow-up time was 4 months, mean follow-up time was 14 months, and 44% of patients had greater than 6 months of follow-up. Conclusions: This review of the experience at our institution since 1990 shows single-fraction radiation therapy to be an effective treatment for cutaneous T-cell lymphoma, with high response rates and very low relapse rates. No significant financial relationships to disclose.