The systemic and hepatic circulation dynamics of 30 mongrel dogs were investigated during and after isoflurane anesthesia at concentration of 1.5, 2.2, and 3.0%. Alveolar and arterial isoflurane concentrations increased rapidly after starting inhalation, and decreased rapidly after stopping of inhalation. At the 3 concentrations, MAC was about 1, 1.5, and 2, respectively. Mean arterial pressure (MAP), heart rate (HR), and cardiac index (CI) all decreased dose-dependently after starting inhalation. After stopping inhalation, MAP recovered rapidly, but the recovery of HR was slow and the recovery of CI was poor. Hepatic arterial blood flow (HABF), portal venous blood flow (PVBF), and hepatic tissue blood flow (HTBF) decreased dose-dependently after starting inhalation. After stopping inhalation, HABF and HTBF recovered rapidly, but the recovery of PVBF was poor. Arterial isoflurane concentrations correlated wiht MAP, CI, HABF, PVBF, THBF, and HTBF. HABF was correlated with MAP, and PVBF was correlated with CI. Systemic vascular rasistance (SVR) and mesenteric vascular resistance (MVR) changed similarly during and after inhalation of isoflurane.