Aims: To compare the effect of addition of Dexmedetomidine (1 ug/kg) and Fentanyl (1 ug/kg) to Ropivacaine (0.2%) in femoral block for potentiation of postoperative analgesia in knee surgeries. Material and methods: After ethical committee approval study was conducted on 50 patients posted for planned knee surgeries. At the end of surgery patients were divided randomly into two groups of 25 each and PNS guided femoral nerve block was given. Group–F received 0.2% Ropivacaine (20 ml) +Inj. Dexmedetomidine 1 µg/kg+ Normal Saline. Total volume 22 ml. Group–Freceived 0.2% Ropivacaine (20 ml)+Inj. Fentanyl 1 µg/kg+ Normal saline. Total volume 22 ml. Hemodynamic monitoring, duration of postoperative analgesia, motor and sensory blockade and sedation were assessed for 24 hours. Results: Duration of sensory and motor block was significantly higher in group D compared to group F; p value <0.001. Duration of analgesic action was found to be significantly higher in patients of group D; p value <0.001. There was significantly lower mean pain score on the VAS among patients in the group D as compared to those in group F; p value < 0.001. Conclusion: The onset and duration of motor and sensory blockade among patients in the group D was significantly quicker and longer as compared to those in the group F. Analgesic duration was also more in the patients of group D and pain scores as measured by VAS were less. Thus from this study we concluded that Dexmedetomidine with Ropivacaine provided better postoperative pain relief as compared to fentanyl with Ropivacaine.