AimTo evaluate gross motor function and associated factors in children with congenital Zika syndrome (CZS).MethodFifty‐nine children (30 males, 29 females) with CZS at a mean (SD) age of 14.7 (3.9), months (range 5–29mo) were evaluated using the Gross Motor Function Measure (GMFM) and classified according to the Gross Motor Function Classification System (GMFCS). Neurological damage was evaluated by neuroimaging. The mothers’ sociodemographic characteristics and general data on the children were obtained from interviews with the mothers and from the children's medical records. Correlational and multiple regression analyses were performed to identify factors associated with these children's motor function.ResultsIn 81% of the children, motor function impairment was severe, classified as GMFCS level V. The overall GMFM score ranged from 5 to 210 (median 18; interquartile range 11), with only four children receiving scores in the D and E dimensions. The factors found to affect motor function were the presence of severe malformations of cortical development and small head circumference at birth.InterpretationAlthough motor impairment may be mild in some children, it is generally severe. Severe malformations of cortical development and small head circumference at birth were factors associated with poorer motor function, reflecting the greater severity of brain damage.What this paper adds Motor impairment is severe in most children with congenital Zika syndrome (CZS). Motor skills are adequate or close to adequate for age in 7% of children with CZS. Severe malformations of cortical development are associated with poor motor control. Small head circumference at birth is also associated with poor motor control.