Introduction: Single action potential causes a brief contraction followed by relaxation and is known as SimpleMuscle Twitch. The twitch may be benign (having no underlying pathology) i.e., may be related to anxiety, stress,psychiatric illness, depression and traumatic events and also may be due to motor neuron disease.Objective: To determine the simple muscle twitch in Exam / Test induced stress in first semester MBBS students onMaterial & Methods: This study was carried out at physiology department LUMHS Jamshoro. In this comparative study, 30 students of first semester MBBS were included. The tool for collection of data was power lab T_125by AD instruments (hardware) and the lab tutor (software) with stimulating bar electrode as transducer. The datacollected before test and after test was analyzed on MS Excel.Results: The result of this study showed that the voltage of current required for muscle twitch to develop in thenar muscle and in fingers during test induced stress was on average 5.85 mA while the current required aftertest (free of stress) was 7.75 mA. The difference is statistically significant.Conclusions: Less voltage was required to develop muscle twitch during mental stress.Keywords: Stress, Muscle Twitch, Power Lab.