Amrinone was given to 18 healthy subjects in doses of 75, 150, and 225 mg in a randomized crossover design. Plasma levels were shown to rise in proportion to dose. The mean plasma AUC, extrapolated to infinite time, was determined for each dose level; the values obtained were 4, 8.18, and 12.35 micrograms . hr/ml for the 75-, 150-, and 225-mg doses. Mean maximum observed plasma concentrations were 1.03, 1.74, and 2.58 micrograms/ml. At higher doses the extrapolated AUC is more variable, but it is linear over the range of 0.73 to 3.81 mg/kg. The apparent first-order terminal elimination rate is not dose dependent and corresponds to a t1/2 of 3.85 hr.