A special-purpose software package has been developed to acquire and analyze analog signals from a whole blood aggregometer. Up to four independent blood samples can be analyzed simultaneously or with arbitrary delays in time. The user menu ensures proper calibration prior to each measurement and provides a real-time graphic display of the signals. From analog/digital converted data, several "derived diagnostic quantities" are calculated. They are constructed with the aim to mimic the process of visual inspection of aggregometry curves and thus place the intuitive diagnostics of blood platelet function on a quantitative basis.