Human myocardium has an amazing ability to contract reliably day-to-day as reflected by the timing events of the cardiac cycle. We measured the mechanical activity of the heart to record cardiac cycle timing events using digital ballistocardiography (dBG) in a group of healthy subjects (N=7; 3 females) with no known cardiovascular disease. We hypothesised that dBG would reliably record the timing events of the cardiac cycle from day-to-day. Subjects (mean ± SD, age= 31.7±10.5yrs) were assessed on three consecutive days (D1, D2, D3), at the same time of the day and under similar conditions in a quite laboratory setting. Each subject had the dBG-300 sensor attached to the skin using solid gel electrodes (single lead EKG). The dBG-300 sensor was placed over the sternum approximately 2cm above the xiphoid process. Thereafter, a 30-second ballistocardiogram was recorded and stored for later analysis. A total of 15 dBG waveforms (heart beats) were analysed for each subject per day and then averaged (Mean±SD). Results showed that average heart rate on D2 (58.4±11.7 bpm) was significantly (ANOVA) lower from D3 (60.2±7.7 bpm), but not D1 (59.1±8.2 bpm). When the dBG data was then corrected for heart rate there were no significant differences between any of the cardiac cycle timing intervals, including Q-wave (EKG) to: atrial systole (AS) (D1=-40.6±12.6msec; D2=-43.5±13.9msec; D3=-44.9±11.5msec); mitral valve close (MVC) (D1=42.6±9.8msec; D2=41.3±11.5msec; D3=42.2±8.1msec); aortic valve open (AVO) (D1=75.5±8.0msec; D2=75.4±9.6msec; D3=72.0±9.8msec); rapid ejection period (REP) (D1=145.1±10.9msec; D2=141.5±10.0msec; D3=138.7±5.7msec); aortic valve close (AVC) (D1=329.7±30.3msec; D2=333.3±28.9msec; D3=331.0±27.2msec); mitral valve open (MVO) (D1=433.7±31.3msec; D2=435.1±29.5msec; D3=436.2±16.0msec); early diastole (ED) (D1=518.9±33.2msec; D2=518.3±29.3msec; D3=519.2±23.6msec); and late diastole (LD) (D1=995.2±160.2msec; D2=1025.6±236.2msec; D3=996.1±139.6msec). The percent difference for these variables day-to-day was 9.7% (AS), 3.1% (MVC), 4.6% (AVO), 1.9% (REP), 1.1% (AVC), 0.6% (MVO), 0.2% (ED), and 5.7% (LD). These data suggest that: 1) day-to-day cardiac cycle mechanics in human subjects is reliable; and 2) digital ballistocardiography can be used to reliably monitor differences in cardiac cycle timing intervals from day-to-day.