Sleeve gastrectomy (SG) is currently considered as a primary bariatric surgery. This is because of its relative simplicity and satisfactory results. As observed with other bariatric procedures, surgeons are confronted with insufficient weight loss or weight regain, insufficient resolution of metabolic disorders, and intractable severe reflux. A retrospective analysis of conversion from SG to Roux-en-Y gastric bypass (RYGBP) was performed to assess weight loss, diabetes resolution, and relief of reflux symptoms. The mean interval between the two procedures was almost 24 months. Eighteen patients underwent conversion from SG to RYGBP for insufficient weight loss (n = 9), severe reflux (n = 6), and persistence of type 2 diabetes mellitus (T2DM) (n = 3). The median follow-up was 15.5 months. Weight loss was significantly improved with a mean percentage of excess of body mass index loss at 64.6 % after conversion versus 47.1 % before conversion. All reflux symptoms were immediately relieved without any medication at the end of the follow-up. The three patients who had an operation for persistence of T2DM are now free of medication. Only one postoperative complication was observed as a small bowel injury, which was treated surgically. Conversion from SG to RYGBP is safe. Severe reflux is definitely treated and is an incontestable indication with this procedure. Additionally, weight loss and diabetes are clinically improved. Our results appear to be similar to those with a primary RYGBP.