Background: Urodynamic studies (UDS) is a simple non-invasive test to assess lower urinary tract function but it may be affected by several factors includes age, sex, voiding volume and voiding position. These interventional parameters become more highlighted while performing UDS in children whose emotional stress control and coping with unfamiliar situation is more difficult. Methods: Seventy six primary school age healthy children underwent screening uroflowmetry in different voiding positions voluntarily. Cases with urinary symptoms, other coexisting diseases, voiding volume less than 20cc or staccato voiding curve were excluded. Washrooms were designed in both western and eastern styles. UDS indexes were compared regarding voiding habits. Results: Comparison of uroflowmetric indexes between different genders and voiding positions showed differences which were not statistically significant but considering the voiding habits, uroflowmetric indexes were significantly different in familiar compare to unfamiliar voiding position. Q-Max was lower and time to Q-Max and micturition time were longer in unfamiliar voiding position. Conclusions: Urodynamic studies in children should be performed in preferred voiding position for each kid considering the culture and voiding habits. Unfamiliar voiding position may turn the uroflowmetry to a stressful experience for child that make him uncooperative and cause misleading results.