Aim of this research was a) the evaluation of the ability of all categories of RG gymnasts to reproduce rhythm and b) to study the differences of that ability among different ages, locating therefore, criteria of choosing gymnasts for the sport, as well as potential coaching deficiencies. The participants of this research were 124 girls in total, from the age of 9 to 15, who were divided in two groups (62 RG gymnasts and 62 non-gymnasts) and three sport-related age categories-levels (pre-juniors, juniors, seniors according to this sport). For the evaluation of the maintenance of rhythm, four devices were used (electric time-switch, device that produces light-stimulus, metronome and bright-signals recording camera). The results showed that the differences between gymnasts and non-gymnasts in kinetic performance of rhythm are significant, however only in the age of pre-juniors. This suggests that RG gymnasts develop the rhythmic ability, which is necessary for their compulsory routines, from an early age. However, this ability does not develop enough in time, thus it equalizes with the rhythmic ability of non gymnasts, as they also mature physically. This fact ensures that the sense of rhythm is indeed a criterion of choosing gymnasts, but also that the RG gymnasts’ training during puberty is so oriented to technical elements that their rhythmic performance doesn’t seem important anymore.