Based on the authors' experience with reconstruction of the heart using three-dimensional echocardiography, the authors assessed the feasibility of three-dimensional reconstruction of brain images using transfontanelle ultrasound in selected cases of infants with abnormal intracranial findings. A conventional 5-MHz ultrasound transducer inside a transducer holder was rotated 180 degrees around its vertical axis using a computer-controlled stepper motor to acquire multiple sequential cross-sections of the brain. The raw digital data of this three-dimensionally recorded dataset were transferred to a PC-based workstation for further analysis. The reconstruction of the three-dimensional brain images and volumetric analysis were undertaken using a new dedicated software capable of three-dimensional reconstruction and volumetric analysis (Echo-PAC-3D, version 1.2 Beta, GE Vingmed, Horton, Norway). The reconstruction of sequential slices from the stored three-dimensional data allowed the visualization of the epicortical extension and volumetric measurements of the focal ischemic infarction in the superior tempoparietal lobe in a 2-week-old newborn with a focal ischemic brain lesion. In other 2-week-old newborns, the extension and volume of a periventricular hemorrhage was visualized by three-dimensional reconstruction of coronal cross-sectional images from the acquired three-dimensional dataset. The three-dimensional reconstruction of the lateral ventricles allowed the three-dimensional visualization and estimation of ventricular dilatation in milliliters in an 8-week-old infant with hydrocephalus. Three-dimensional reconstruction of brain images and volume estimation of brain lesions and cavities by ultrasound may provide new insights into the morphology and extension of ultrasonographically visible brain lesions.