Objective: Relative dose intensity (RDI) is the ratio of delivered dose intensity of chemotherapy to standard dose intensity. In this study, we sought to determine the prognostic significance of RDI in patients with epithelial ovarian cancer (EOC). Methods: A retrospective analysis of chemotherapy naïve patients treated between 2001 and 2008 with intravenous taxane and platinum was performed. RDI was calculated as the delivered dose intensity (total dose delivered/total time of therapy) divided by standard dose intensity calculated for each regimen and compared to progression-free survival (PFS). Multivariate recursive partitioning survival analysis was utilized. Results: 138 EOC patients completed initial taxane/platinum-based chemotherapy following surgical cytoreduction. The most common reasons for dose delays and reductions were thrombocytopenia (38%) and neutropenia (31%). 24% of treatment delays were due to social reasons such as transportation constraints or scheduling conflicts. The average RDI was 90% (range, 24-126%). The mean PFS was 31 months (range, 3-117). Patients that achieved an RDI between 70% and 110% had a mean PFS of 32 months compared to 20 months in patients with an RDI of < 70% or > 110% (p = 0.046). 14 patients (10%) had a RDI of < 70%. Conclusions: RDI is a significant predictor of survival in patients with EOC. Effort should be made to achieve an RDI of at least 70%. Dose reductions and treatment delays could be minimized by utilizing prophylactic colony stimulating factors and educating patients about the importance of adhering to their treatment schedule. © 2011 Elsevier Inc.