Treatment options for patients with chronic refractory immune thrombocytopenic purpura (ITP) are limited. Because combination immunosuppressant therapy appeared to be effective in ITP and other disorders, we used this approach in patients with particularly severe and refractory ITP. In this retrospective, observational study, we determined the response (platelet count above 30 x 10(9)/L and doubling of baseline) among 19 refractory ITP patients. Treatment consisted of azathioprine, mycophenolate mofetil, and cyclosporine. The patients had failed a median of 6 prior treatments, including splenectomy (in all except 1). Of 19 patients, 14 (73.7%) achieved a response lasting a median of 24 months, after which time 8 (57.1%) relapsed. Of the 8 relapsing patients, 6 responded to additional treatments. Of the 14 patients who achieved an initial response, 2 (14.3%) remained in remission after eventually stopping all medications. Severe adverse events did not occur. Combination immunosuppressant therapy can produce a rise in the platelet count that is sometimes sustained in refractory ITP patients.