Initial clinical results are reported from a new real time, 2-dimensional ultrasound scanner modified for adult cephalic applications. An optimized transducer design and the use of the dynamically focused phased array imaging system have resulted in ultrasound tomograms of the brain which are significant improvements over previous attempts. Horizontal and coronal images of the ventricles, the corpus callosum and other midline structures are routinely displayed in a 45 degrees sector format. In addition, pulsating cerebral arteries are displayed in real time. Quantitative information can be obtained concerning cerebral vascular patency by using the selectable M-mode feature of this system. The results indicate that real time ultrasound tomography has potential for clinical application.