In the Cardiac-Renal-Pulmonary Clinic of Northwestern University, an experiment was begun in October, 1972 to study the impact of a computerized medical record summary system (NUCRSS) on process and outcome of care. 419 randomly selected patients were randomly assigned to two groups: an experimental group (NUCRSS available) and a control group (NUCRSS absent). Approximately 300 variables per subject, representing parameters of process and outcome of care, were collected, entered into a computer data base and cleaned. Because the experimental and control groups have remained intact, new data for the 479 subjects could now be collected after four years in the study. We proposed that four year data be collected on a selective basis emphasizing outcome of care and that all data (new and old) be analyzed. Thus the effects of NUCRSS on process and outcome of care over a span of four years can be determined. A small pilot analysis of three variables in the existing data base has yielded encouraging results.