Aim: This study aimed to investigate effect of the age of acquisition of gross motor functions on functional motor impairment in children with cerebral palsy. Material and Method: Six hundred seventy one children with cerebral palsy who were diagnosed by a pediatric neurologist and referred to Hacettepe University, Department of Physiotherapy and Rehabilitation, Cerebral Palsy Unit were included this study and acquisition ages of gross motor functions were asked to the parents. Functional motor impairment was determined with Gross Motor Function Classification System. Ethics committee approval was received by Hacettepe University Medical Faculty Ethics Committee, Faculty of Health Sciences (Number: HEK 06/60). Results: Clinical types of the patients with cerebral palsy included 625 (93.1%) spastic, 32 (4.8%) dyskinetic, 10 (1.5%) ataxic and four (0.6%) mixed type. According to Gross Motor Function Classification System 152 (22.7%) of the children were in level I, 102 (15.2%) were in level II, 111 (16.5%) were in level III, 60 (8.9%) were in level IV and 246 (36.7%) were in level V. The median age of acquisition of sitting independently was nine months in level I, 12 months in level II and 24 months in level III. The median age of acquisition of crawling was 12 months in level I, 18 months in level II and 48 months in level III. The median age of acquisition of walking independently was 18 months in level I and 33 months in level II. Conclusions: Age of acquisition of gross motor functions gradually increased as the severity of motor impairment increased, as we expected. We believe that the results of this study will provide information regarding prognosis of gross motor impairment in children with cerebral palsy. (Turk Arch Ped 2012; 47: 191-196)