Background and Objectives: In our study we aimed to investigate the effect of bupivacaine and levobupivacaine on QT, corrected QT (QTc), and P wave dispersion durations during spinal anesthesia in cesarean section.,Methods: Sixty parturients scheduled for elective cesarean section in ASA I-II risk groups were included in the study. Baseline electrocardiographic (ECG) records of the patients were obtained in the operation room. Heart rate (HR), non-invasive blood pressure (NIBP), peripheral oxygen saturation (SpO(2)) and respiration rates (RR) were recorded. Venous cannulation was performed with 18G cannula and fluid preload made with 10 mL.kg(-1). Lactated Ringer solution. After fluid preload, second ECG recordings were taken and the patients were randomly separated into two groups. Group B (n = 30) received 10 mg of bupivacaine and Group L (n = 30) received 10 mg of levobupivacaine for spinal anesthesia. ECG recordings were repeated at 1, 5 and 10 minutes after spinal block. HR, NIBP, SpO(2), RR and sensory block levels were also recorded at the same time intervals. At predetermined time intervals of spinal anesthesia, P wave dispersion (Pwd), QT dispersion (QTd), and QTc dispersion (QTcd) durations were measured from ECG records. QT and QTc durations are calculated with Bazzett formula.,Results: There was no difference between two groups according to block levels, hemodynamic parameters, Pwd, QTd, QTc and QTcd durations.,Conclusion: Bupivacaine and levobupivacaine may be preferred in spinal anesthesia in pregnant patients who have extended Pwd and QTcd preoperatively. (C) 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.