Splenectomy is definitive treatment for idiopathic thrombocytopenic purpura (ITP) because it removes both the sites of autoantibody producing cells and also the major site of platelet destruction. The purpose of this study was to evaluate long term results of splenectomised patients with ITP and to determine predictor factors for good response. A 167 patients with chronic ITP (136 females, 31 males), median aged 35 years (17-74) was splenectomised after 2 to 160 months (Median 12) from diagnosis of ITP. Indications for splenectomy were: 6 weeks of steroid therapy with platelet count below 10 x 10(9)/l or 3 months with platelet count under 30 x 10(9)/l, or treatment with prednisone above 30 mg more of 6 months to increase platelet count over 30 x 10(9)/l, or repeated relapses. Postoperative complications developed in 16 patients (9.5%), 3 of them died (1.8%) due to thromboembolism and 17 patients discontinued later controls. During follow up to 172 months (Median 62) 111/147 splenectomised patients were in remission (75.5%), 99 in complete (above 100 x 10(9)/l), 12 in partial (50-100 x 10(9)/l) and 36 patients (24.5%) were relapsed (below 50 x 10(9)/l). Remission was achieved in 79/88 patients (89.8%) with good response to prednisone before splenectomy toward 32/62 patients (51.6%) with poor response to prednisone (p < 0.01). Remission was obtained in 9/11 patients (81.8%) who responded well to intravenous immune globulin (0.4 g/kg x 5 d) and only in 1/8 who did not (p < 0.05). Higher response rate was achieved in patients under 40 years of age (81.6%) than in older ones (63.4%) (p < 0.05). No difference was shown between sex and time intervals (3, 6, 12, 24, 36 or over 36 months) from diagnosis to splenectomy. Splenectomy is an effective treatment of refractory ITP with response rate of 75.5% after median follow up of 62 months. In our patients better results on splenectomy were associated with age less than 40 years, good responses to steroid, and intravenous immune globulin.