The longitudinal growth in 139 patients with cystic fibrosis (CF) was investigated from birth until the age of 19 years. Already at birth weight and length were reduced (weight: -0.83 +/- 0.13 SDS in girls, -0.44 +/- 0.13 SDS in boys; length: 0.55 +/- 0.13 SDS in girls, -0.39 +/- 0.14 SDS in boys; mean +/- SEM). Both variables showed a further decline until diagnosis was established (weight: -1.57 +/- 0.21 SDS in girls, -1.46 +/- 0.25 SDS in boys; length: -1.15 +/- 0.32 SDS in girls, -1.03 +/- 0.52 SDS in boys; mean +/- SEM). Six to 12 months after diagnosis length improved and reached the 25th percentile in both sexes. Height and weight followed the 25th percentile throughout childhood. Growth velocity was fairly normal during this period. There was a loss in percentiles of both height and weight after the age of 8 years and the pubertal growth spurt was delayed and reduced. However, the 25th percentile was reached again in the adolescent period. At the age of 19 years median height was 161.5 cm in girls and 173 cm in boys, both representing the 25th percentile. Using a sensitive statistical method for analysis of growth data we present CF specific growth curves for height, weight and growth velocity. There was no significant effect of pulmonary colonization with Pseudomonas aeruginosa on growth velocity.