Group L- patiens will receive 3.5 ml of drug containing o.5% levobupivacaine and 25 mcg of fentanyl.

Group R- patiens will receive 3.5 ml of drug containing o.75% Ropivacaine and 25 mcg of fentanyl.

After administration of study drug onset of sensory and motor blockade will be assessed. Segmental sensory level of anaesthesia will be assessed by patient s response to pin prick every 2 min till 20 min and then every 10 min till highest level is achieved. time of onset of sensory block will be noted. Time of sensory block regression will be assessed from maximum block height attained to regression till L1 dermatome. Duration of sensory block is defined as time from intrathecal injection to regression of pin prick sensation to L1 dermatome. Motor block will be assessed every 5 min for 30 min and then every 15 min till recovery of motor blockade to modified bromage score of zero. Time of regression of motor block will be assessed from modified bromage score of 3 to zero. Duration of motor block is defined as time from intrathecal injection to regression of motor block to bromage score of zero.Intraoperative pulse rate, mean arterial blood pressure and oxygen saturation will be recorded every 2 min till 20 min and then every 5 min till end of surgery. Any side effects like nausea, vomiting, pruritis, bradycardia or hypotension will be recorded. In the post operative period the time to first analghesic demand will be noted and patient will be given rescue analgesia in the form of injection diclofenac sodium 1.5 mg/kg IV (intravenous) if VAS >3 and requirement of same will be noted for 24 hours. After completion of study, observations obtained will be tabulated and analysed using appropriate statistical methods.