To analyze growth patterns of children with CP between countries; to examine differences in growth; and to assess the fit of growth charts. Cross-sectional study in children with CP from 2 to 19 years old, 399 from Argentina and 400 from Germany. Growth measures were converted into z-scores and compared to WHO reference and US CP growth charts. Generalized Linear Model was used to analyze the growth expressed as mean z-scores. 799 children. Mean age 9 years (± 4). Compared to the WHO reference, the decrease in Height z-scores (HAZ) with age in Argentina (− 0.144/year) was double that in Germany (− 0.073/year). For children in GMFCS IV–V, BMI z-scores (BMIZ) decreased with age (− 0.102/year). Using the US CP charts, both countries showed decreasing HAZ with age, in Argentina (− 0.066/year) and in Germany (− 0.032/year). BMIZ increased more among children with feeding tubes (0.062/year), similar in both countries. Argentinian children with oral feeding decrease their Weight z-score (WAZ) by − 0.553 compared to their peers. With WHO charts BMIZ presented an excellent fit for GMFCS I–III. HAZ presents a poor fit to growth references. BMIZ and WAZ presented a good fit to US CP Charts. Growth differences due to ethnicity also act in children with CP, and are related to motor impairment, age and feeding modality, possibly reflecting differences in environment or health care.