In order to derive standard curves for height, weight, head circumference (OFC), weight-for-height, and height velocity, we obtained serial measurements in 95 patients with the Rubinstein-Taybi syndrome. Fifty individuals were part of an American study and 45 were ascertained in the Netherlands. Prenatal growth appears to be normal in the Rubinstein-Taybi syndrome, but height, weight, and OFC rapidly fall below the 5th centile in the first few months of life. Height velocity is somewhat below the mean but within the normal range except for the lack of a pubertal growth spurt. This phenomenon probably contributes to the short stature which is seen in these patients. Males are overweight for height during childhood while females are overweight during adolescence. The average OFC in males is smaller than in females. In general only a minority of adult patients are microcephalic.