In acute-phase response, the use of amino acids is redirected to supporting the synthesis of proteins for host defence and tissue repair. Fibrinogen is one of these proteins, and its plasma levels commonly increase in acute-phase conditions. After hepatectomy, this pattern may be modified by the variable impact of postoperative liver dysfunction. Our study was performed to specifically assess and quantify this aspect. Data were collected prospectively on 82 hepatectomized patients; 62 recovered normally, 20 had major complications (most commonly sepsis). Plasma fibrinogen and a large series of complementary variables were determined preoperatively and at postoperative days 1, 3 and 7 in all patients and until recovery, or death in those with complications. Multiple regression analysis showed that postoperative changes in fibrinogen (deltaFIB, micromol/l) were simultaneously related to the number of resected liver segments (NSEG), total bilirubin (BIL, micromol/l), aspartate aminotransferase (AST, U/l, n.v. 5-45), albumin (ALB, g/l), prothrombin activity (PA, % of standard reference), age (AGE, years) and basal preoperative fibrinogen (PFIB, micromol/l): deltaFIB = -0.51(NSEG) - 0.71(Log(n)BIL) - 0.74(Log(n)AST) + 0.11(ALB) + 0.09(PA) - 0.06(AGE) - 0.55(PFIB) + 7.74 (n=362, r2=0.68, p<0.001). In addition, an early postoperative tendency for low fibrinogen was associated with the subsequent development of complications or death. Our study quantifies the impact of size of hepatectomy and dysfunction of residual liver in modulating postoperative fibrinogen level and suggests that failure of fibrinogen to increase may signal an unfavorable condition limiting up-regulation of acute-phase response and increasing liability to complications.