We investigated the influence of sex and age in postural sway during sit‐to‐stand (STS) in children and adolescents of 5–15 years. We evaluated sway during STS in 86 typical participants. STS was divided into three phases: preparation, rising, and stabilization. We calculated for each phase: area, anterior–posterior, and medial–lateral velocity of center‐of‐pressure sway. We applied a stepwise multiple linear regression model to determine if age and sex might be predictors of postural sway during STS. Only age was associated with sway, accounting for between 6.5% and 14.6% of the variability in sway during STS. The age of the subject influences postural sway during STS, but in a small amount. This variable should be taken into account as a variable of control in the assessment of dynamic postural control. Moreover, postural stability during STS was not associated with the sex of the participants.