BACKGROUND The risk of postoperative liver dysfunction (PLD) in patients with injured livers, such as in hepatocellular carcinoma (HCC), is still not negligible. Phenacetin metabolism test can reflect hepatic functional reserve in patients with chronic hepatic damage. The aim of this study was to assess the ability of phenacetin metabolism test to predict PLD in patients with HCC receiving partial hepatectomy. MATERIAL AND METHODS Forty-nine patients with HCC undergoing partial hepatectomy between 2014 and 2016 were included at Huashan Hospital, Fudan University. The phenacetin metabolism test was used to assess the hepatic functional reserve. The ratio of total plasma paracetamol to phenacetin was collected in patients at 2 h after oral administration of 1.0 g phenacetin, recorded 5 days prior to surgery and on the fifth postoperative day. Phenacetin metabolism test, Child-Pugh classification, and Model for End-Stage Liver Disease (MELD) score were correlated with PLD. RESULTS Of 49 patients with HCC, 13 patients (26.5%) had PLD. The association between the ratio of total plasma paracetamol to phenacetin and PLD was statistically significant (p=0.0061) and the correlation coefficient was -0.647 (p=0.0082). The phenacetin metabolism test showed a larger area under the receiver operating characteristic (ROC) curve value (0.735) than Child-Pugh's classification (0.472) and MELD score (0.419). Using the calculated cutoff of 0.6, the lower ratio of total plasma paracetamol to phenacetin preoperatively was chosen to specifically identify patients with PLD. The sensitivity and specificity were 0.657 and 0.892, respectively. CONCLUSIONS Phenacetin metabolism test could be preoperatively used in predicting PLD in HCC patients receiving partial hepatectomy. It potentially provides better prediction than Child-Pugh classification and MELD score.