Purpose: For safe hepatic resection, the preoperative estimation of hepatic functional reserve in the predicted remnant liver may be more important than that in the entire liver. The purpose of this study was to find the minimal GSA-Rmax in the predicted remnant liver (GSA-RL) using functional imaging that predicts postoperative hepatic failure and, by so doing, avoid this complication. Methods: One hundred and seventy-eight patients were admitted for elective hepatectomy. Conventional liver function, and 15 min retention rate of indocyanine green (ICGR15) were carried out preoperatively. The GSA-Rmax was calculated according to a radiopharmacokinetic model and then, using the SPECT images, we calculated the regional GSA-Rmax in the predicted residual liver (GSA-RL), depending on the operative procedures. The volume of the predicted residual liver (LV-RL) was calculated on the basis of CT images. Results: Surgical procedures consisted of 98 sub-segmentectomy cases, 41 mono-segmentectomy cases, 31 di-segmentectomy cases and 8 tri-segmentectomy cases. The preoperative LV-RL correlated well with the GSA-RL in patients with normal liver however, there was no such correlation in those with chronic hepatitis or cirrhosis. Postoperative major complications such as hepatic failure, hyperbilirubinemia, bleeding (requiring re-operation), ascites, liver abscess, bile leakage and pleural effusion were recorded for 45 patients after subsegmentectomy, 25 patients after monosegmentectomy and 23 patients after di- and tri-segmentectomies. Fourteen patients had more than one complication. All of 7 postoperative hyperbilirubinemia occurred in the patients with GSA-RL < 0.15. Two patients died of postoperative liver failure one to two months after the operation. These two patients GSA-RL values were 0.078 and 0.090, respectively and severe discrepancies between the GSA-Rmax in the remnant liver and ICGR15. Conclusions: Our data suggest that GSA-RL might be a practical and reliable diagnostic method for estimating the postoperative functioning hepatocyte volume and useful for making a final decision on surgical procedure, regarding the extent of liver resection in order to avoid postoperative hyperbilirubinemia or hepatic failure.