Background: To explore the clinical significance of baseline volumetric body composition parameters evaluated with computerized tomography (CT) and their changes after 3-4 months from treatment initiation of targeted therapy in patients with metastatic renal cell carcinoma (mRCC). Method: This study included 108 Caucasian mRCC patients (Male/Female: 77/31) treated with targeted therapy. Volumetric body composition parameters including total adipose tissue index (TATI), subcutaneous adipose tissue index (SATI), visceral adipose tissue index (VATI) and skeletal muscle index (SMI) values were depicted from CT images at third lumbar vertebra level through volumetric measurement software. Kaplan-Meier method and the long test were used for estimation of progression free survival (PFS) and overall survival (OS). Univariate and multivariate analyses were done to determine the associations between clinic-pathologic variables including VBC and survival outcomes. Results: The median PFS and OS of all patients were 11 months and 46 months in patients respectively. After adjustment for the variables including international mRCC database consortium (IMDC) risk score, only a high skeletal muscle index (SMI) was associated with better PFS (HR: 0.975, P=0.015). The independent predictors for OS were VATI (HR 1.005, P=0.024), SATI (HR: 0.976, P=0.019) and TATI (HR: 0.982, P=0.035) in addition to IMDC risk score. Conclusion: Our findings revealed that while SMI was the only significant determinant parameter for PFS among VBC parameters, TATI, VATI, and SATI were determined as independent predictors for OS in addition to IMDC risk score.