To assess the postoperative outcome of jaundiced patients and to select the optimal timing for surgical intervention, indocyanin green (ICG) concentrations in the bile were measured after biliary decompression in patients with obstructive jaundice. The maximal excretion rate of ICG in the bile was calculated as a function of time (ICG Bmax). Among 59 patients with positive ICG Bmax values, morbidity was 15.2% and postoperative hospital mortality was 3.3%. However, the morbidity and mortality in nine patients with values between -0.5 and 0 were 88.8 and 44.4%, respectively. The 13 patients with in ICG Bmax below -0.5 had a 76.9% morbidity and a 61.5% mortality. The patients with ICG Bmax values below 0 showed a significantly higher morbidity and mortality than positive ICG Bmax patients. In patients showing ICG Bmax values below -0.5, surgery is contraindicated despite intensive postoperative care. The ICG Bmax value improved according to the increasing effect of biliary decompression. The index is useful not only as a prognostic index in the early phase of biliary decompression but also as an index of bile secretory capacity at a given time. By means of time course measurement of this index, the suitable time for operation can be determined. The ICG Bmax is a useful and reliable indicator in the assessment of hepatobiliary functional reserve in jaundiced patients after biliary decompression and prior to further surgical intervention.