In current practice, the length of epidural catheter that should be left in the epidural space is not standardised for effective postoperative analgesia. This prospective, randomised, double-blinded study aimed to determine the most appropriate length of epidural catheter that should be inserted into the epidural space for postoperative analgesia. We recruited 102 women and assigned them into three study groups (3, 5 and 7 cm insertion). An epidural catheter was inserted and epidurography was performed. Postoperatively, mean pain scores, motor and sensory levels, and any complications associated with the epidural catheter were recorded. No statistically significant difference for mean postoperative pain score was found at all study timings. Motor and sensory blockade was also statistically insignificant. Unilateral sensory analgesia developed in one patient in the 7 cm group and epidural catheter dislodgement was observed in four patients in the 3 cm group. In order to minimise catheter-related complications for postoperative analgesia, the most appropriate length that an epidural catheter should be left in the epidural space is 5 cm.