Some studies showed that the increase of tumor size has a negative effect on survival in colon cancers. Our study aims to assess the effects of tumor volume on lymph node positivity and prognosis in stage pT3 colon cancers. All patients who underwent surgery for colon cancer in our clinic were evaluated retrospectively. The study included 213 patients who were diagnosed with colon adenocarcinoma and reported as pathologic. Preoperative abdomen computed tomography scans were used for measurements of tumor volume. Tumor volumes were compared according to the pathological lymph node involvement. Cut-off values were determined with ROC analysis. The cases were divided into groups according to the determined cut-off value and data compared. Mean tumor volume was found to be higher in the lymph node-positive group (p=0.01). The higher number of removed lymph nodes and lymph node positivity was detected more in cases that were above the cut-off value (p=0.003 and p=0.004, respectively). The mean survival time was 37.3±1.3 months. There was no correlation between tumor volume and the overall survival time (p=0.21). According to data comparison of the lymph node positivity, Kaplan-Meier analysis showed that the increase of the N stage reduces the 5-year survival rate (for the N0, N1, N2 stages, 60%, 52%, 35%, respectively). Tumor volume is correlated with lymph node involvement. It has been shown that increasing the N stage has a negative effect on prognosis. Our study showed that tumor volume has no significant impact on survival but may have an indirect effect on prognosis.