The aim of the present study was to clarify the association between preoperative liver function and complications after hepatectomy. The study included 11,686 patients registered in the National Clinical Database for 2015 for whom data on indocyanine green at 15 min (ICG15) and hepatectomy were available. The patients were divided into four groups: group A (ICG15 <10%; n = 5,661), group B (ICG15 10% to <20%; n = 4,381), group C (ICG15 20% to <30%; n = 1,173) and group D (ICG15 >30%; n = 463). Hepatectomy procedures were classified as partial resection (n = 3,934), systematic subsegmentectomy (n = 2,055), monosectionectomy (n = 2,043), bisectionectomy (n = 2,993) and trisectionectomy (n = 208). Complications were classified using the Clavien-Dindo classification (CD) and evaluated by ICG15 category and procedure type. Complications more severe than CD III increased significantly as the operation time lengthened and the intraoperative bleeding volume increased (P < 0.001). ICG15 category was positively associated with operative death, >CD III complications, surgical site infection (SSI), liver failure, and intractable ascites for many of the major hepatectomy procedures, but not with bile leakage. More complications were observed in patients outside the Makuuchi criteria than in those within the criteria. Operation time and intraoperative bleeding volume are significantly associated with severe postoperative complications in patients undergoing hepatectomy. ICG15 is a good indicator predictive of operative death, >CD III complications, SSI, liver failure and intractable ascites.