Background and Aims: Shoulder surgery is associated with significant postoperative pain. A continuous interscalene brachial plexus block provides an excellent postoperative analgesic modality for early rehabilitation and recovery. The aim of this study was to compare the efficacy between Ropivacaine 0.2% and Bupivacaine 0.125% with respect to Quality of analgesia, Motor block, Patient satisfaction, Hemodynamic effects and Complications. Methods: Hundred patients scheduled for shoulder and upper arm surgeries between 1875yrs of ASA 1, 2, 3 were prospectively randomized by sealed envelope technique into 2 groups of 50 each. GroupA: 0.125%Bupivacaine, GroupB: 0.2% Ropivacaine. Patients with COPD, localized infection and Catheter dislodgement were excluded. Ethics committee approval was granted and patients consent was taken. Data was analyzed with the help of MannWhitney test, Chisquare test and SPSS software version 21.0. Interscalene catheter was placed using ultrasound following which all patients received general anaesthesia. At the end of the surgery, 10 ml of either bupivacaine or ropivacaine was given followed by continuous infusion at 5ml/ hour post extubation that continued upto 48 hours. A 5ml bolus of same drug was given as rescue analgesia. Quality of analgesia was assessed by VAS score, motor block was assessed by hand strength scoring them on a scale of 1 to 3. Results: VAS score remained less than 2 in both groups(p >0.05). Motor blockade was 19% in Bupivacaine, compared to 2% in Ropivacaine (p <0.05). Catheter dislodgement was found to be 16%. Conclusion: Ropivacaine 0.2% and Bupivacaine 0.125% provide good and comparable postoperative analgesia with bupivacaine causing statistically significant motor blockade.