Introduction: About 23-46 per cent of children with Cerebral Palsy suffer from sleep problems. It adversely impacts on learn ing, mental functioning, emotional function, the behavioural and social function of school-aged children. So a trial to investigate the association between sleep problems of pre-school and school-aged Cerebral Palsy (CP) children to their gross motor (GM) function. Objective: To examine the association between sleep problems and gross motor function of the pre-school and school-aged children with CP. Methodology: Sixty-two CP children of 3-10years age participate in the observational co-relational study. The Child__ampersandsignrsquo;s Sleep Habit Questionnaire (CSHQ) and Gross Motor Function Classification System, Expanded and Revised (GMFCS-E__ampersandsignamp;R) were administered to measure sleep problems and gross motor function respectively. Results: Data are analyzed by two-tailed Spearman correlation and found strong association persists between sleep problem and gross motor function of preschool and school-aged children with CP ( r =0.868,p=0.00). The severity of sleep behaviour at various GMFCS -ER levels were analyzed by Kruskal-Wallis Test (F=11.33, p=0.001) and the post hoc test was applied by the Bonferroni method found as follows 5-1__ampersandsigngt;4-1__ampersandsigngt;3-1__ampersandsigngt;2-1__ampersandsigngt;2-5. Conclusion: Sleep problem affects in achieving the gross motor function of Pre-school and school-aged children with CP