The aim was to investigate the effects of a six-month balance intervention based on Ayres therapy on dynamic balance in 5-6-year-old preschoolers born with biological risk factors. Sixty-four preschoolers participated in this study, and were assigned to an experimental group (VR, born with risk factors), a control group 1 (KR, born with risk factors) and a control group 2 (KI, born with no risk factors). VR group attended a 30-min balance training two times a week for six months. KR and KI groups followed the regular Physical Education schedule. A beam-walking task was used to measure dynamic balance. Significant distance differences were found for VR group. Balance values of VR group approached to those who did not attend the intervention. Neither results of pre- and post-tests show significant gender differences. Training with instability training devices can be an effective way to improve balance performance for preschoolers with developmental delay.