The development of CATHCOM, a cardiac CATHeterization laboratory COMputer system, is discussed. CATHCOM provides flexible and complete analysis of hemodynamic data for a single laboratory. It supports both automatic and computer-interactive methods of analysis in a manner which permits the physician to control the quality of the analysis performed by the system. Outputs from the system include both graphic and alphanumeric displays. All catheterization data are stored permanently on diskette. The system has been extensively engineered to provide efficient, user-friendly operation.