The objective of the analysis was to determine the effectiveness of re-treating patients with ovarian cancer, primary peritoneal cancer, and fallopian tube cancer with carboplatin after being deemed platinum resistant. From a database period January 1, 1996, to December 12, 2002, 34 patients were identified who received nonplatinum agents before resuming treatment with carboplatin. The median age was 65 years, and a median of two nonplatinum chemotherapy (range 1-5) prior to re-treatment with carboplatin was received. The median platinum-free interval from the time platinum was last received to re-treatment with carboplatin was 15.2 months (95% confidence interval [CI] 12.6-17.9; range 6.2-47.0). A median number of four cycles of carboplatin (range 1-11) was received. Two patients (5.9%) achieved partial response, while 21 patients (61.7%) achieved stable disease. The median time to progression for these 23 patients after re-treatment with carboplatin was 5.7 months (95% CI 5.2-6.3; range 1.8-15.3). Twenty-seven patients have died, and all patients have progressed. Seven patients are still receiving salvage therapy. The median overall survival from the time deemed to be platinum resistant is 23.2 months (95% CI 20.1-26.4). Patients who have been deemed platinum resistant may still benefit from platinum re-treatment after an interval of treatment with nonplatinum agents.