Objective To investigate the levels of immunoglobulins and complement in children with cerebral palsy. Methods 59 children with cerebral palsy were assessed with Gross Motor Function Classification System (GMFCS), and the serum levels of immunoglobulin (Ig)G, IgA, lgM, complements C3 and C4 were measured in the children with cerebral palsy and other 61 children without cerebral palsy (controls). Results The serum levels of IgG, IgA, lgM, complement C3 and C4 decreased significantly in the children with cerebral palsy compared with the controls (P<0.001). There was significant difference in the levels of IgG, IgM, and complement C4 among cerebral palsy children of different grades of GMFCS (P<0.05), but not in the levels of IgA and complement C3 (P>0.05). Conclusion There is humoral immune dysfunction in some children with cerebral palsy, which may associated with the severity of the disease.