||Systolic time internal (STI) tests are a noninvasive technique for evaluation of left ventricular heart function. Manual methods for calculating STI are time consuming, very tedious, and require, lengthy mathematical calculations which are prone to error. A computerized method for measuring STIs using and x-y digitizer tablet as the input device was developed. The STIs are recorded on photographic paper as in the manual method. This recording paper is then placed on the x-y digitizer tablet and the points required for calculation of the STI are selected and digitized by the operator. The computer performs all of the required calculations. Patient demographic data is entered via a cathode ray terminal (CRT). The CRT is also used to control editing of the data. When data entry is completed the STI data is stored in a disc file. Data can be retrieved from the disc and any parameter reviewed or corrected. When the operator confirms that all data is correct, the computer generates a hard copy patient report. This report lists the demographic data, STI measurements for each heart cycle selected, average STI values, STI index values, a derived ejection fraction, and a clinical impression. Approximately ten minutes are required to enter the data, review the results, and print the patient report. The manual method requires at least one hour to perform the STI calculations and does not produce a printed report. The entire computerized system requires less than a thousand dollars worth of additional equipment if the user already has the computer, CRT, and printer. This computerized STI reporting system changed the status of the STI testing at the hospital where it was developed from that of a research test to that of a useful clinical procedure.