Valsalva maneuver is naturally done during behaviors such as coughing, heavy lifting, urinary excretion, and defecation. Despite the fact that both the body position and the valsalva maneuver may affect the cardiovascular autonomic system activity, so far, few studies were conducted about the effect of body position on heart rate responses to the valsalva maneuver. The aim of this study is to assess heart rate response to the valsalva maneuver in the standing, sitting, lying, and squatting postures in healthy young males. The design of this study determines that each subject (of the total subjects n=19) has to position in each of the four postures with a ten minute interval. Meanwhile standard valsalva maneuver, ECG lead II continuously is recorded for five min. Then, time and frequency domains of heart rate variability criteria are calculated. The inclusion criteria are being male and age of 19 to 24 and the exclusion criteria are chronic diseases (such as diabetes, hypertension, epilepsy, etc.), smokers, and chronic medication consumers. The interventions of the study include sitting, standing, and squatting positions in comparison with supine position. The mean and standard deviation of sequential R-R intervals are the primary outcomes of the study.