The short-term effects of nifedipine (10 mg administered sublingually) on functional liver plasma flow, measured by calculating the extrarenal clearance of sorbitol, were investigated in 12 normal volunteers and 40 patients with cirrhosis scored according to Child-Pugh classification. Nifedipine significantly increased functional liver plasma flow in healthy subjects (23%, p < 0.0001) and in patients with cirrhosis in the Child-Pugh class A group (19%, p < 0.001); in patients in the Child-Pugh class B group functional liver plasma flow was not modified, whereas in the patients in the Child-Pugh class C group it was significantly reduced (- 7%, p < 0.02). The mean arterial pressure showed a significant reduction in all groups studied. According to the pathophysiologic meaning of functional liver plasma flow, it is suggested that nifedipine meets criteria for an ideal test substance to evaluate the functional reserve of the liver. Furthermore, when used with the Child-Pugh classification, its effect on functional liver plasma flow may be useful to improve the efficiency of the Child-Pugh classification, in establishing the prognosis of patients with cirrhosis.