1. The pharmacokinetics of nisoldipine (10 mg) was assessed in 10 healthy subjects after single dose and multiple dose oral administration. Apparent liver blood flow was measured, using ICG before and during the absorption phase of nisoldipine. 2. Apparent liver blood flow was increased both on acute and short-term administration of nisoldipine, basal flow being lower on multiple dosing than on acute administration (P less than 0.02). 3. A positive relationship was found between the increase in apparent liver blood flow during absorption of nisoldipine and the flow-dependent part of the total AUC of nisoldipine. 4. The findings of this study indicate that a variable liver blood flow response during the absorption phase of nisoldipine contributes to the pharmacokinetic variability of the drug, both on acute and multiple dose administration.