The hemodynamics, contractility and compliance of the right ventricle were examined during the early postoperative phase in 9 children operated for correction of tetralogy of Fallot. The same assessments were made in 5 patients after the transventricular closure of ventricular septal defects (control group). A further reduction of the PRV/LV quotient was observed in the Fallot group during the first 3 hours postoperatively. The contractility of the right ventricle (dp/dt max) was greatly reduced in all cases. The pressure/volume relationship of the right ventricle showed severe disturbance in compliance. The type of correction (with/without outflow tract patch or monocusp) did not appreciably affect the results. The hemodynamic changes observed in the control group (VSD) were considerably less pronounced. Apparently it is not the ventriculotomy but the infundibulectomy which is the traumatic factor of corrections in the area of the right ventricular outflow tract.