Our objective was to evaluate the effect of itraconazole on the pharmacokinetics of atenolol in healthy volunteers. In a randomized cross-over study with two phases, 10 healthy volunteers had 200 mg itraconazole orally or placebo for 2 days b.i.d., and in the morning of day 3, one hour after the last ingestion of itraconazole or placebo, each subject received 50 mg atenolol. The plasma concentrations of atenolol and its excretion into urine were measured up to 33 hr. Blood pressures and heart rate were recorded up to 10 hr. Itraconazole had no statistically significant effect on any of the pharmacokinetic or pharmacodynamic variables of atenolol. If anything, itraconazole increased the area under the plasma concentration-time curve (+12%; P = 0.159), peak plasma concentration (+19%; P = 0.165), and amount of atenolol excreted into urine (+13%; P = 0.166) suggesting a slight increase of atenolol bioavailability. It can be concluded that itraconazole does not have a clinically relevant effect on the pharmacokinetics of atenolol.