Pharmacokinetics of eltoprazine in male and female beagle dogs was studied in two separate cross-over experiments after administration of different intravenous and oral doses. After intravenous administration of 0.5 mg.kg-1, the mean volume of distribution was 5.7 +/- 1.1 l.kg-1. Clearance was 25.5 +/- 1.4 ml.min-1.kg-1. About 25% of the doses was excreted in urine, resulting ina renal clearance of 6.1 +/- 1.4 ml.min-1.kg-1. The mean elimination half-life (t1/2) after intravenous dosing was about 2.6 h. After oral dosing the plasma peak levels (Cmax) were proportional with the dose. The mean time to reach Cmax (tmax) varied between 1.5 and 1.9 h, and t1/2 was about 2.4 h, which was not significantly different (p greater than 0.05) from the half-life obtained after intravenous dosing. Plasma pharmacokinetics after single and multiple dosing of 4 mg.kg-1 showed no difference. Absolute bioavailability was 67% +/- 20%.