The aim of this study was to assess reliability of the Ariel Computerized Exercise System (ACES) ’multifunction exerciser’. Twenty-three healthy women completed three sets, three repetitions each, of maximal isokinetic supine bench press at two different velocities, slow (10/s) and moderate (25/s). The following performance parameters were studied: peak and average force, peak and average power, and total work. The experiment was repeated for two days. Intraclass correlation coefficients (TC[2,1]) varied between 0.947 and 0.755 at 10°/s and between 0.861 and 0.654 at 25°/s. The standard error of the measurement (SEM), the smallest detectable difference (SDD), and the coefficient of variation (CV) indicated that it is possible to achieve reliable and clinically relevant measurements with the ACES.