Endomyocardial biopsy has had limited utilization for the diagnosis of myocardial disease in the pediatric population. Through the use of echocardiography for guidance, we attempted 155 consecutive biopsies in 33 patients. A successful biopsy was performed 151 times, including 48 (31%) in infants less than 6 months of age. Biopsies were performed with a right internal jugular approach using 3F, 5F, and 7F bioptomes. A combination of apical four-chamber and parasternal short-axis views could visualize the passage of the bioptome into the ventricle and the action of the jaws. There was no case of ventricular perforation. After biopsy one transplant recipient was left with an increase in the amount of preexisting tricuspid regurgitation by color flow mapping echocardiography. These results demonstrate that echocardiographically guided endomyocardial biopsies may be safely performed over a wide range of patient sizes. The increased portability, lack of radiation exposure, and the simultaneous visualization of the bioptome and chamber wall combined with these results indicate that echocardiographically guided endomyocardial biopsies should be considered the technique of choice for the pediatric population.