Objective: To evaluate longitudinal growth in Turner’s syndrome (TS) over the first 3 years of life. Methods: Growth of 47 patients with TS was compared with that of 40 age-matched control girls by using an analysis according to the Infancy-Childhood-Puberty and bi-exponential models. Results: A mean of 1.2 SDs were lost before birth and a total of 3.0 SDs were lost by age 3 years. According to the Infancy-Childhood-Puberty model, intrauterine growth retardation contributed –1.24 SDs, a 5-month delay in childhood growth spurt contributed –0.96 SDs, and slow childhood growth contributed an additional –0.8 SDs by age 3 years. The bi-exponential analysis disclosed a quasi-linear first exponent and a confining second exponent, which merged at age 18 months in control subjects and 24 months in patients with TS. The first exponent confers an average annual growth rate of 8.4 cm/y in control subjects and 6.7 cm/y in patients with TS. Conclusions: Intrauterine growth retardation and the initial 3 years of life contribute most of the deficit in the final height of patients with TS. These data provide a reference of standards for longitudinal growth in patients with TS at age 3 months to 3 years. (J Pediatr 2000;137:460-4)