Background: Precocious puberty may reduce final adult height, and affected children may suffer social and emotional problems. The efficacy of treatment with a long acting agonist analogue of the gonadotropin releasing hormone (aLHRH) has been well demonstrated. Aim: To evaluated the efficacy of a new formulation of aLHRH (leuprolide, Lupron®) for the suppression of gonadotropin activation and clinical signs of puberty. Material and methods: Eleven children (ten females) with idiopathic central precocious puberty, with a mean chronological age of 7.5±1.8 years and a bone age of 9.7±1.8 years were recruited. Testicular volume in the male was 15 ml. In females, Tanner stage for breast development was between 2-4 and mean ovarian volume was 2.3±0.8 ml. They were treated during 18 months with aLHRH, 11.25 mg administered intramuscularly every three months. Results: Clinical, hormonal and ultrasonographic signs of puberty regressed in all patients. The degree of suppression of LH was 87.7±5.1% at the end of the 18 months. No significant changes in bone mineral content were observed during the treatment period. Conclusions: Leuprolide (aLHRH) 11.25 mg, injected every three months, is effective for the control of central precocious puberty and allows to reduce the number of yearly injections from 12 to 4