Salvage therapy of patients with advanced, relapsed and refractory multiple myeloma (MM) is often limited by poor marrow reserve and multi-organ impairment. In particular, renal failure occurs in up to 50% of such patients, and this further limits the use of conventional chemotherapy. Thalidomide, both alone and in combination with dexamethasone, has been demonstrated to be useful in patients with advanced MM, as responses could be achieved in 30-60% of the cases. From May 2000 to November 2003, 20 consecutive MM patients (15 males, five females, median age 66.5 yr) with stage III relapsed/refractory MM and renal failure, defined as serum creatinine >130 mmol/L, gave their informed consent to be enrolled in a clinical trial aimed at evaluating the efficacy and the toxic effects of thalidomide. Three patients were undergoing chronic haemodialysis during the time of entry in the study. Eight patients have been treated with thalidomide as a single agent, at a starting dose of 100 mg/d, that was to be increased to 400 mg/d in case of good tolerance. Twelve patients have been treated with thalidomide at the maximum dose of 200 mg/d plus dexamethasone 40 mg/d for four consecutive days every 4 wk. A >50% decrease in serum or urine M component was observed in nine patients (45%), seven of whom have been treated with thalidomide + dexamethasone and three with thalidomide alone. Six additional patients achieved a minor response (>25% paraprotein decrease); the total response rate was thus 75%. Median response duration was 7 months (range 2-24 months). Four patients were refractory to treatment. Recovery of a normal renal function was observed in 12 of 15 responsive patients, two additional patients, in chronic haemodialysis, showed a reduction of serum creatinine. Toxicity profile of thalidomide with or without dexamethasone was comparable with that observed in patients with a normal renal function. In conclusion, our data show that thalidomide can be safely administered in patients with advanced MM and renal failure.