Noninvasive methods have become an important part of the diagnostic process for evaluation of cardiovascular anatomy and function in adults and in the young. Because there is a multiplicity of noninvasive methods presently available, in some cases with overlapping capabilities, there has been some confusion as to which constitutes the method of choice in a given clinical circumstance. The reviews that follow outline some of the practical strengths and limitations of two methods (echocardiography and radionuclide cardiography), hopefully thereby providing some rationale for choosing the more appropriate technique in the approach to specific clinical problems. We have found that the information available from radionuclide and from ultrasound studies frequently is complementary and that the most optimal diagnostic results often are obtained when they are combined. Since advances in technique and improvements in instrumentation are occurring continually in both of these areas, we have tried to provide only an overview. Further investigations and clinical experience will help to define the specificity, sensitivity, and capabilities of these methods in terms of present and future applications.