Background/Aim: In the choice of reconstructions, digestive and absorptive disturbances, resulting in weight loss after subtotal gastrectomy, remain a problem. The aim of this study was to compare fat absorptive function after Billroth I (B-I) and Roux-en-Y (RY) reconstructions after subtotal gastrectomy for gastric cancer. Methods: A 13C-labeled mixed triglyceride breath test was performed in 31 patients after subtotal gastrectomy and in 15 healthy volunteers to assess fat digestive and absorptive function. Seventeen B-I reconstructions and 14 RY reconstructions were performed after subtotal gastrectomy. Fat digestive and absorptive function was determined by percent 13CO2 cumulative dose at 7 h. Relationship between fat absorptive function and perioperative factors were analyzed. Results: Gender distribution, mean age, pathological staging, level of lymph node dissection, preservative procedure of the vagus nerve and mean follow-up period in the two surgical groups did not differ significantly. Only the type of reconstruction (p = 0.024) was associated with differences in fat digestive and absorptive function by univariate analysis: B-I reconstruction was superior to RY reconstruction. Conclusions: Fat digestive and absorptive function after B-I reconstruction was superior to that after RY reconstruction, probably because the B-I reconstruction was the procedure that permitted food passage through the duodenum.