Cladribine is a purine analogue that is resistant to degradation by adenosine deaminase. We describe the efficacy of cladribine monotherapy in 8 patients with relapsed or refractory indolent non-Hodgkin lymphoma. The median age of the patients was 57 years. All patients were given 1-3 courses of cladribine monotherapy at 0.09 mg/kg/day continuous infusion for 7 days. Although all patients had been treated with rituximab and CHOP-like regimens, the response rate was excellent (85.7%). Thus we consider that cladribine is the first treatment of choice in the patients with relapsed or refractory indolent lymphoma.