D-Trp<sup>6</sup>-LHRH was tested in 6 girls 1–8 years old and 7 boys 2–10 years old with precocious puberty. All children had advanced bone age, breast or testis enlargement and a pubertal LH response to LHRH. 60 µg LHRH-A/kg body weight was given intramuscularly on days 1 and 21 and thereafter every 4 weeks for 6–21 months. In girls, breast enlargement disappeared and mean uterus size decreased within 6 months. Mean ovary length decreased from 25.0 ± 1.9 to 16.0 ± 2.7 (p < 0.02). In boys, mean testis volume decreased from 8.0 ± 1.1 to 6.7 ± 1.4 ml (p < 0.05) within 6 months. In both sexes, growth velocity decreased significantly and bone maturation was reduced. Plasma levels of estradiol or testosterone and FSH levels decreased significantly within 3 weeks. The LH response to LHRH was reduced to normal prepubertal values after 7 weeks. No secondary clinical or biochemical escape occurred. No side effects occurred except for transient vaginal bleeding in one girl after the first and second injection. No antibodies to LHRH-A were detected in the patients’ sera. This study demonstrates the ability of a delayed release formulation of D-Trp<sup>6</sup>-LHRH to suppress pituitary and gonadal secretion and pituitary response to LHRH for as long as 2 years of therapy. This treatment appears to be more efficient in treating both clinical and biochemical abnormalities than does treatment with inhibitory steroids. Additionally the method of administration is more practical and ensures better patient compliance.