Based on the efficacy of thalidomide in multiple myeloma and on its synergy with dexamethasone on myeloma plasma cells, we evaluated the combination of thalidomide (100 mg/d, with 100-mg increments every 2 weeks, up to 400 mg) and dexamethasone (20 mg on days 1-4) every 21 days in 31 patients with primary amyloidosis (AL) whose disease was refractory to or had relapsed after first-line therapy. Eleven (35%) patients tolerated the 400 mg/d thalidomide dose. Overall, 15 (48%) patients achieved hematologic response, with 6 (19%) complete remissions and 8 (26%) organ responses. Median time to response was 3.6 months (range, 2.5-8.0 months). Treatment-related toxicity was frequent (65%), and symptomatic bradycardia was a common (26%) adverse reaction. The combination of thalidomide and dexamethasone is rapidly effective and may represent a valuable second-line treatment for AL.