A 58-year-old woman with a 15-year history of chronic plaque psoriasis was diagnosed with gastric marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. Topical treatment and ultraviolet radiation for therapy of psoriasis had been of limited efficacy. The patient received intravenous treatment with 0.12 mg/kg per day of 2-chlorodeoxyadenosine (2-CDA) over 5 days for management of MALT lymphoma, as it was resistant to eradication of Helicobacter pylori. A total of six cycles were administered from June 1999 until November 1999 (cumulative dose 244.8 mg 2-CDA). After 2 months of 2-CDA administration, psoriatic skin lesions improved significantly, and after 3 months, complete remission of skin lesions was observed. Ongoing complete remission of the MALT lymphoma could be achieved after six cycles of 2-CDA administration. After a follow-up period of 34 months, no recurrence of psoriatic lesions has occurred. The patient is at present free of psoriatic plaques and gastric MALT lymphoma. The course of disease in our patient provides evidence for sustained therapeutic efficacy of 2-CDA in chronic plaque psoriasis in the absence of severe side effects except asymptomatic lymphopenia.