In Japan, the Billroth I and Billroth II operations have been used for reconstruction after a distal gastrectomy for gastric cancer. However, a Roux-en-Y reconstruction is increasingly performed to prevent duodenogastric reflux. We herein discuss the indications for Roux-en-Y in gastric surgery and review the literature to determine its advantages and disadvantages. Indications for Roux-en-Y reconstruction after a distal gastrectomy are: (a) When the primary lesion has directly invaded the duodenum or head of the pancreas, the Billroth I operation is likely to result in local recurrence near the anastomosis; (b) in addition, the Billroth I operation is not indicated after a subtotal gastrectomy due to an unacceptable anastomotic tension; reconstruction using a nonphysiological route is therefore preferred. The advantages of Roux-en-Y reconstruction after a distal gastrectomy include a reduction of reflux gastritis and esophagitis, a decreased probability of gastric cancer recurrence, and a reduction in the incidence of surgical complications such as ruptured suture lines. The disadvantages of Roux-en-Y reconstruction include the possible development of stomal ulcer, an increased probability of cholelithiasis, increased difficulty with an endoscopic approach to the ampulla of Vater, and the possibility of Roux stasis syndrome. The principal advantage of a Roux-en-Y reconstruction is that it is less likely than the Billroth I operation to result in duodenogastric reflux. Roux-en-Y reconstruction or Billroth I operation can only be selected after considering their respective advantages and disadvantages.