BACKGROUND To provide postoperative pain relief is a prime duty of health care providers. Failure to relieve pain is morally and ethically unacceptable. Post-operative pain may results in adverse effects such as: a) Physiological Changes: Reduced pulmonary functions, e.g. vital capacity, tidal volume, functional residual capacity; sympathetic stimulation; reduced the physical activity of patients; thereby increasing the risk of venous thrombosis. b) Psychological disturbances: Anger, Resentment, Depression, Adversarial Relationship with Doctors, Insomnia. Aim of this study was 1. To investigate whether "Postoperative analgesia with Nalbuphine is longer than Pentazocine". 2. To investigate whether "Side effects/complications are less with Nalbuphine as compared to Pentazocine".