Vinflunine is a novel tubulin-targeted agent that is currently indicated as a monotherapy in bladder cancer patients. The recommended dose of 320 mg/m² is given as an intravenous infusion once every 3 weeks. Vinflunine is metabolized through CYP3A4 and mainly eliminated via the feces. A phase I trial was designed to explore the tolerability and pharmacokinetics of vinflunine in cancer patients with ranging degrees of liver dysfunction (LD). A sequential design was used for patient accrual, with the objective of determining the maximum tolerated dose (MTD) and the recommended dose (RD) of vinflunine in 3 groups of increasing LD levels. Vinflunine and its only active metabolite 4-O-deacetylvinflunine were quantified in serial whole blood samples. PK parameters were derived and compared between LD groups and with a reference PK database. Vinflunine and 4-O-deacetylvinflunine PK parameters were not affected in any of the explored LD levels. Geometric mean values for vinflunine total clearance were 47.8, 37.5 and 45.4 L/h in the 3 groups of increasing degrees of LD, as compared to 42.5 L/h in reference patients with no LD. No relationship was found between vinflunine clearance and the presence or absence of cirrhosis, nor was it found with the presence or absence of liver metastasis or with liver-related biochemical parameters. Based on the observed tolerability profile, the recommended doses of i.v. vinflunine are 320 mg/m², 250 mg/m² or 200 mg/m² for patients with increasing degrees of liver dysfunction.