Splenectomy is a common therapy for adults with chronic idiopathic thrombocytopenic purpura (ITP). Thisstudy was designed to estimate both the short-term surgical non-response rate and the long-term relapse rate after laparoscopic splenectomy. A systematic review was conducted of articles published between January 1, 1991 and January 1, 2008. Selection criteria included: chronic ITP, study enrollment in 1990 or later, > or =12 months of follow-up, > or =15 patients with ITP, > or =75% of patients at least 14 years of age, not HIV positive, not undergoing a second splenectomy, and type of performed splenectomy clearly reported. Data were pooled across studies to estimate rates. We identified 170 articles, of which 23 met our inclusion criteria (all observational studies). These studies represent 1,223 laparoscopic splenectomies (71 or 5.6% were converted to open splenectomy during surgery). The pooled short-term surgical non-response rate among the 18 studies reporting data was 8.2% (95% CI 5.4-11.0). The pooled long-term relapse rate across all 23 studies was 43.6 per 1,000 patient years (95% CI 28.2-67.2). This translates to an approximate failure rate of 28% at 5 years for all patients undergoing splenectomy. Studies with shorter durations of follow-up had significantly higher pooled relapse rates than studies with longer follow-up (P = 0.04). Laparoscopicsplenectomy is effective for most patients. Splenectomy may have higher initial relapse rates, particularly, in the first 2 years after surgery, and the rate may decline over time. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.