Nineteen (12 male, 7 female) children, who have received craniospinal irradiation for the treatment of a brain tumour distant from the hypothalamic-pituitary axis, resulting in growth hormone (GH) deficiency (CS-PRGHD), have been treated with GH. Eight have completed growth. Comparison has been made with the growth of seven untreated children, whose heights and growth rates at presentation were normal despite GH deficiency secondary to irradiation. GH produced a significant increase in growth velocity over the first 3 years' treatment in CS-PRGHD patients with a mean first year increment of 3 cm/year. Patients, treated to completion of growth, showed a significant increase in leg length standard deviation (SD) score (delta SDS + 0.2) compared to that of the untreated (delta SDS - 0.9) (P less than 0.05). Sitting height SD scores decreased irrespective of GH therapy (by -1.7 for the treated and -2.2 for the untreated). The onset of puberty in the irradiated patients occurred at a mean bone age of 10.7 years in males and 9.9 years in females. This limited the time available for GH therapy. These factors resulted in a decrease in standing height SDS of 0.9 at completion of GH therapy in CS-PRGHD, but a decrease of 1.7 in those not treated with GH. Thus GH therapy failed to induce "catch-up" growth in irradiated patients, but it did prevent further loss of adult stature, with a mean final height SD score of -3.4 in CS-PRGHD patients.