Multiple myeloma (MM) is commonly associated with anemia. Several causes have been implicated but inadequate erythropoietin (Epo) production appears to be important. This single-institute open-label, non-comparative clinical trial was undertaken in order to evaluate serum Epo levels in patients with MM and to study the efficacy and toxicity of recombinant human Epo (rHuEpo) in the treatment of MM-associated anemia. MM patients with a baseline hemoglobin (Hb) level of < 11 g/dl received rHuEpo 150 U/kg 3 times/week subcutaneously, with a possible dose increase to 300 U/kg if no response was observed after 4 weeks. The study was designed for 12 weeks, although some responders continued rHuEpo. The study endpoints were determined by an increase in Hb and a decrease in blood transfusion requirements (BTR). Seventeen patients were enrolled in the study. The median serum Epo level was 150 mU/ml (range 11-232). Four patients did not complete the study for reasons unrelated to rHuEpo, but to their underlying MM. Twelve patients (70.6%) responded with an increase in their Hb levels. One patient (5.9%) responded partially. The median Hb level rose from 9.4 g/dl (range 7.3-10.7) at study commencement to 12.5 g/dl (range 9.0-15.2). Six of the 11 patients who were transfusion dependent enjoyed a complete abolition of BTR. The response was also interpreted as an improved quality of life: 3 patients reported a decrease of 1 level in their WHO performance status (PS) score; in 8 patients, the PS declined by 2 grades and 1 patient enjoyed PS reduction by 4 scores. Six patients continue to receive rHuEpo up to 18 months, with a good response and a smaller maintenance dose. Four patients reported flu-like symptoms, 2 suffered from a local irritation and 1 experienced a transient controlled elevation of blood pressure. CONCLUSIONS (1) Pretreatment endogenous serum Epo levels were relatively low in all patients studied with MM-associated anemia; (2) rHuEpo was well tolerated in these patients; (3) rHuEpo was highly effective in the treatment of anemia in MM, and (4) the response to rHuEpo is characterized by an increase in Hb levels, a reduction in BTR and an improvement in the WHO PS score.