To evaluate the results of radiotherapy in patients with primary cutaneous B-cell lymphoma (CBCL) classified according to the criteria of the World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification. Multicenter, 20-year, retrospective, cohort analysis. Eight dermatology departments collaborating in the Dutch Cutaneous Lymphoma Group. From 1985 until 2005, a total of 153 patients with CBCL were initially treated with radiotherapy with curative intent. These cases were classified according to the WHO-EORTC classification and consisted of 25 primary cutaneous marginal zone lymphomas (PCMZLs), 101 primary cutaneous follicle center lymphomas (PCFCLs), and 27 primary cutaneous large B-cell lymphomas, leg type (PCLBCLs, LT). Interventions Local radiotherapy with a median dose of 40 Gy (range, 20-46 Gy) applied to all visible skin lesions. Complete remission rate, relapse rate, 5-year relapse-free survival, 5-year overall survival, and 5-year disease-specific survival. Complete remission was reached in 151 of 153 patients (99%). Relapse rates for PCMZL, PCFCL, and PCLBCL, LT were 60%, 29%, and 64%, and the 5-year disease-specific survival was 95%, 97%, and 59%, respectively. The PCFCLs presenting on the legs had a higher relapse rate (63%) and a much lower 5-year disease-specific survival (44%) than PCFCLs at other sites (relapse rate, 25%; 5-year disease-specific survival, 99%). Radiotherapy is a suitable treatment for a large group of patients with CBCL. However, patients with PCFCL presenting with lesions on the leg and patients with PCLBCL, LT display a more unfavorable clinical course and should therefore be treated with more aggressive treatment modalities.