This will be a comparative study between two cohorts of patients undergoing Roux-en-Y Gastric bypass. One cohort (75 patients) will receive FDA approved Exparel® (liposome bupivacaine injection solution) injections intra-operatively at time of incision site closure. The control cohort (75 patients) will receive 0.25% bupivacaine injection solution at the time of incision site closure. The medication for the control group is our current standard of care. The primary end point is post-operative pain at 24 and 48 hours measured by the Visual Analog Scale (VAS). Comparison will be made between cohorts. All subjects enrolled in the study will be evaluated per nursing protocol with the verbal numerical analog scale. At 24 and 48 hours a member of the research team will administer a 2-part questionnaire containing the VAS and the Revised American Pain Society Post-Operative Questionnaire (APS-POQ-R). The latter is validated for assessment of the patient's experience of pain and it hindrance to daily activity in the post operative period.