We present growth curves of 1,726 Turkish children with Down syndrome (DS) between 0 and 18 years of age and investigate the factors that affect growth including congenital heart disease (CHD) and hypothyroidism. Longitudinal measurements of height, weight, and head circumference (HC) were assessed and accompanying major malformations were recorded. Growth curves were monitored using Cole's LMS method. The mean birth length was reduced by −0.5 standard deviation (SD) for Turkish standards in both boys and girls. Pubertal growth spurt of the girls with DS started 1 year earlier, their puberty duration was short and pubertal annual growth rate was inadequate, and as a result the final height was −3.06 SD for Turkish standards. Although the age at onset of pubertal growth spurt and puberty duration of the boys were similar to normal population, their pubertal annual growth rate was inadequate; thus the final height was −2.56 SD for Turkish standards. The final weight values were similar to normal population. The mean HC values of DS children were corresponded to −0.9 SD for Turkish standards at birth; however after 6 months values were below −2 SD. The final HC values were −1.02 SD for boys and −2.21 SD for girls for Turkish standards. We observed that weight was decreased in DS children with severe CHD during first 4 years of life. However, there is no statistically significant difference in values of height and head circumference between patients with or without severe CHD group. In addition, hypothyroidism had no effect on growth in DS patients. © 2012 Wiley Periodicals, Inc.