Growth, age at menarche and spontaneous GH secretion were studied in girls after treatment for acute lymphoblastic leukemia (ALL). These girls had normal prepubertal growth but subnormal pubertal growth. Mean final height was 1 SD less than expected before puberty. The average age at menarche was significantly lower than the normal mean for Swedish girls. The mean 24-hour GH secretion was severely blunted and there was no increase during puberty. We suggest that girls treated for ALL, including CNS irradiation, have a relative GH insufficiency which becomes clinically obvious only when the girls cannot respond to the increased demands for GH in puberty.