DNA polymerase delta 1 catalytic subunit (POLD1 or POLD1/p125) plays a crucial role in DNA synthesis and proofreading during the semiconservative genome replication. Mutations of POLD1 are associated with abnormal cell division in various human tumors. However, the significance of altered POLD1 expression in malignant diseases and its usefulness as a prognostic factor is not fully understood. This study aimed to determine POLD1 immunoexpression levels in paired sections of tumor and normal kidney derived from 56 patients with clear cell renal cell carcinoma (ccRCC) and evaluate the significance of POLD1 protein as a potential prognostic factor in ccRCC.Tissue samples were collected from 56 patients (27 females and 29 males, mean age 62.6, range=27-83 years) who underwent nephrectomy due to ccRCC. Paired tissue samples were obtained from the tumor and unchanged part of the kidney. The expression of POLD1 protein was assessed by immunohistochemistry. Clinical and pathological data of patients were also collected. Patients were followed-up and the median time of observation period was 39.3 months.The study revealed a significantly higher POLD1 nuclear expression in ccRCC tumor tissue samples and this was correlated with longer survival rates (better prognosis) of ccRCC patients.POLD1 immunoreactivity in ccRCC postoperative material could be helpful as a prognostic marker in the ccRCC patient group.