The aim of this study was to investigate the relationship among functional classification systems, the Manual Ability Classification System (MACS), the Gross Motor Function Classification System (GMFCS), and the functional status (WeeFIM) in children with spastic cerebral palsy (CP). One hundred and eighty-five children with spastic CP (101 males, 84 females), 65 (35.1%) diparetic, 60 (32.4%) quadriparetic, and 60 (32.4%) hemiparetic children, ranging from 4 to 15 years of age with a median age of 7 years, were included in the study. The children were classified according to the GMFCS for their motor function and according to the MACS for the functioning of their hands when handling objects in daily activities. The functional status and performance were assessed by using the Functional Independence Measure of Children (WeeFIM). A good correlation between the GMFCS and MACS was found in all children (r = 0.735, p < 0.01). There was also a correlation between the GMFCS and WeeFIM subscales according to subtypes and all parameters were correlated at the level of p < 0.01, the same as the MACS. There was no difference in the MACS scores among the age groups of 4-7, 8-11, and 12-15 years (p > 0.05). The use of both the GMFCS and MACS in practice and in research areas will provide an easy, practical, and simple classification of the functional status of children with CP. The adaptation of both of these scales and WeeFIM and using these scales together give the opportunity for a detailed analysis of the functional level of children with spastic CP and reflect the differences between clinical types of CP.