Using quantitative cineangiography we studied left ventricular size and function in 15 patients (aged 1 day to 15 years) with double inlet left ventricle. Our purpose was to assess how ventricular volume and performance change with age and palliative surgery in patients with and without restriction to pulmonary flow. Ventricular volumes were calculated using Simpson's rule method; end-diastolic volume was also stated as a percentage of predicted total (combined right and left) ventricular volume. Ejection fraction and systolic pressure to end-systolic volume ratio were calculated as indexes of ventricular function. Our results suggest that ventricular size is inadequate for a septation procedure in patients with restriction to pulmonary flow but increases after shunting operation. In patients without restriction to pulmonary flow, ventricular volume is adequate for a septation procedure during the first months of life, but it tends towards reduction, along with obstruction of the interventricular communication, after pulmonary artery banding. Ejection fraction is slightly lower than in left ventricle of heart with biventricular atrioventricular connexion, but it does not decrease with age, at least during the first 15 years of life. Systolic pressure to end-systolic volume ratio also does not decrease with age, but it is lower in patients with excessive pulmonary flow or atrioventricular valvar regurgitation.