Altered mean platelet volume (MPV) is found in several malignancies. Remarkably, there is little consensus on using the value of MPV in the prognostic evaluations of renal cell carcinoma (RCC). The aim of this study is to examine the feasibility of MPV value as a prognostic indicator of RCC. The retrospective study recruited 306 consecutive RCC patients between January 2009 and December 2009. The relationships between MPV and clinicopathological characteristics were analyzed. Kaplan-Meier method and Cox regression were used to evaluate the prognostic impact of MPV. Of the 306 RCC patients, low MPV levels were detected in 61 (19.9%) patients. Reduced MPV was associated with histology types, T classification, UCLA Integrated Scoring System (UISS) category, and Mayo clinic stage, size, grade, and necrosis score (SSIGN) category (P < 0.05). Patients with decreased MPV had significantly shorter survival time than patients with normal MPV (P < 0.001). Cox regression analysis revealed that reduced MPV was an independent prognostic factor for overall survival (hazard ratio, 1.758; 95% confidence interval [CI], 1.083-2.855, P = 0.023). Moreover, the prognostic accuracy of TNM stage, UISS, and SSIGN prognostic models were improved when MPV was added. In conclusion, reduced MPV is identified as an independent predictor of adverse clinical outcome in RCC.