A total of 63 patients with hGH deficiency were recruited, of whom 59 are evaluable. Somatrem (Somatonorm), 4 IU three times/week, was given either subcutaneously or intramuscularly. Height velocity increased from a mean of 4.7 +/- 2.1 cm/year before therapy to 8.2 +/- 2.6 cm/year in the 15 patients who have been followed for 1 year. In patients with isolated hGH deficiency height velocity increased similarly to the whole group, but in those with multiple pituitary hormone deficiencies the pretreatment and on-treatment growth velocities were lower. Of four children who had previously received spinal irradiation, three experienced only a small increase in height velocity on Somatonorm treatment; the fourth showed a considerable increase in height velocity. Anti-hGH antibodies were present in about 80% of the children tested after 12 months of treatment, but the titres and binding capacities were low. Anti-ECP antibodies were also detected, but again the titres were low, and 39% of the children tested had anti-ECP antibodies before treatment commenced.