This study aims to investigate the effect of relative age effect on the development of fundamental movement skills in boys and girls. Data were collected from primary school first grade 22 boys and 33 girls students aged 5-6 years. Three age groups have been formed as 68-76, 77-80 and 81-89 months for boys, 71-75, 76-80 and 81-84 months for girls, respectively. Fundamental movement skill levels have been determined by the Test of Gross Motor Development. This study showed that the body height of boys and the body mass index of girls were significantly differentiated according to age groups. Only leap in male and side gallop skill in females were also significantly differentiated according to age groups. The limited effect of the relative age effect in this study may be due to the inactive lifestyle of children, the lack of pre-school movement education, and interactions between inadequate socio-economic and environmental conditions in Turkey. [Selected Paper of 7th World Conference on Educational Technology Researches (WCETR-2017) 20-22 April 2017 AAB College, Pristina, Republic of Kosovo.]