The hemodynamic effects of the class III drug D-sotalol and of the beta adrenergic receptor antagonist D,L-sotalol were compared in 16 rats (2 mg/kg i.v.). A group with NaCl-infusion served as control (n = 10). Besides measurements in the intact circulation isovolumic registrations were performed to examine the left ventricular myocardial function without interferences. D,L-sotalol significantly reduced the dp/dtmax (61%) and the peak isovolumic left ventricular pressure (64%). It lowered the heart rate by 13% and slightly increased the mean aortic pressure to 107% (p less than 0.05). D-sotalol, in contrast, caused only a very transient reduction of the dp/dtmax and was comparable to the controls already 5 min after injection. The results demonstrate, that the D-enantiomer is largely avoid of the hemodynamic effects of the racemic D,L-sotalol after intravenous injection.