Background Revisional gastric bypass (R-RYGB) surgery is utilized for the management of inadequate weight loss or weight regain observed after some cases of bariatric surgeries. Data on the mid-term effectiveness of primary gastric bypass (P-RYGB) compared with R-RYGB (e.g., post sleeve gastrectomy/gastric banding) are controversial. Methods Retrospective chart review of all patients who received P-RYGB and R-RYGB (January 2011-June 2015) at our center. One hundred twenty patients who underwent P-RYGB and 34 R-RYGB who completed 18 months follow-up were included. We compared the effectiveness of P-RYGB with R-RYGB by assessing four anthropometric, two glycemic, and four lipid parameters, as well as the control of type 2 diabetes (T2DM), hypertension, dyslipidemia (remission, improvement, persistence, relapse, de novo), mortality and complications rates. Results A comparison of the effectiveness of P-RYGB with R-RYGB at 18 months revealed no significant differences in patients' age, gender, and preoperative BMI between groups. However, patients who received P-RYGB had lower mean weight (P = 0.001) and BMI (P < 0.001), reflected by a higher mean delta BMI (P = 0.02), total weight loss percentage (TWL%) (P < 0.0001) and excess weight loss percentage (EWL%) (P < 0.0001). No differences in glycemic parameters, lipid profiles, control of T2DM, hypertension, and dyslipidemia were observed. No death is reported and complication rates were comparable. Conclusions Although R-RYGB effectively addressed inadequate weight loss, weight regain, and recurrence of comorbidities after restrictive bariatric surgery, R-RYGB resulted in inferior weight loss compared with P-RYGB. Neither procedure differed in their clinical control of T2DM, hypertension, and dyslipidemia. Both procedures exhibited comparable complication rates.