Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that has been widely used in both primary research, as well as clinical treatment of neuropsychiatric disorders. While some previous studies have examined the reliability of single pulse TMS protocols, few have done a systematic evaluation of the influence of pulse shapes and current directions of TMS on test-retest reliability and variability of motor-evoked potential (MEP) measurements.The aim of this study is to investigate the test-retest reliability and variability of MEPs induced by single pulse TMS protocols from four combinations of pulse shapes and current directions of TMS (TMS waveform).Twenty (20) healthy right-handed participants took part in the study. Participants were stimulated with four conditions of TMS waveform in three repeated sessions within the same day. TMS protocols investigated were resting motor threshold (RMT), active motor threshold (AMT), stimulus intensity for inducing 1 mV peak-to-peak MEP amplitude (SI1mV), corticospinal excitability measurements with inter-stimulus intervals (ISIs) of 5, 10, and 15 s; input-output curves, and cortical silent period.Preliminary results showed no significant differences in mean MEP amplitudes and latencies for all three ISIs within the four TMS waveform conditions. Variability of MEP measurements was comparable across the three ISIs. Reliability results showed excellent to moderate test-retest reliability for all protocols for the four TMS waveform conditions.This systematic evaluation does shed more light on protocols and TMS waveforms that induce reliability and less variable measurements.