Objective: The main objective of this prospective and observational study is to investigate the effect of preoperative hospitalization period on early postoperative cognitive dysfunction (POCD) development in patients undergoing total hip replacement surgery under regional anesthesia. Materials and Methods: Between November 2013 to September 2014, 64 patients were enrolled the study. Test scores were obtained on the initial admission day (MMT1), 24 hours prior to surgery (MMT2) and 24 hours after the surgery (MMT3). Patients were divided into two groups according to MMT scores as “no cognitive dysfunction” (Group 1) and “cognitive dysfunction” (Group 2). Differences between groups were evaluated statistically. Statistical significance level was set as p<0.05 in a 95% confidential interval. Results: POCD incidence rate was calculated as 43.8% in all patients. Preoperative hospitalization duration was significantly higher in patients with POCD when compared to patients without POCD (p<0,001). The factors which affect POCD development were found to be advanced age (p<0,001), high ASA scores (p=0,004), presence of comorbid disease (p=0,025), duration of operation (p=0,018) and decreased postoperative hematocrit levels (p=0,014). Conclusion: In this study, we observed patients with early POCD had a relatively longer pre-operative hospitalization period when compared to patients without POCD. We consider that the prolonged preoperative hospitalization periods may contribute to increased POCD incidence rates in patients with risk factors.