The present study contributes to the understanding of gross motor development in babies with Down's syndrome. Also, it facilitates the comprehension of the efficiency of the early motor stimulation as well as of beginning it as early as possible. We worked with two groups of babies with Down's syndrome, beginning the early motor training in each group, separated by three months, during the first 18 months of life. The results indicate that on average, the early motor stimulation in Down's syndrome babies is more effective when it begins earlier. (Contains 2 tables and 4 figures.)