Radioimmunotherapy with Yttrium-90 ((90)Y) ibritumomab tiuxetan (IT) has been shown to be effective in systemic B-cell lymphomas. We conducted a pilot study to evaluate the outcome and assess complications of (90)Y IT therapy in patients with primary cutaneous B-cell lymphomas (PCBCL). Ten patients, all but one, with relapsed PCBCL were included and treated with rituximab (250 mg m(-2)/body surface) on days 1 and 8 followed by a single dose of (90)Y IT (11-15 MBq kg(-1)). The overall response rate was 100%. The complete response rate was 100%. The median time to relapse was 12 months. Ongoing remissions were achieved in four patients (median follow-up 19 months). Transient and reversible myelosuppression (grade 3-4) was the most frequent adverse event. Radioimmunotherapy with (90)Y IT is an effective treatment in relapsed primary cutaneous follicle centre lymphomas and diffuse large B-cell lymphoma leg-type. Further investigations in controlled randomised clinical trials evaluating the role of (90)Y IT versus rituximab in PCBCL are needed.