A review of automatic data processing in the cardiac catherization lab is presented. The emphasis placed on on-line manometry, indicator dilution and off-line quantitative ventriculography. The system organization is described and several specific examples given to illustrate the level of detail necessary to specify such a system. The clinical use of the system is described together with an evaluation of the original design goals in terms of the actual performance of the system. A few unexpected benefits have emerged with respect to quality control and reliability, but one of the original design goals, speeding up the catheterization procedure, has proven to be unrealistic. The next logical steps in the software and hardware evolution are described with the emphasis placed on making the system a more effective tool for the clinician.