OBJECTIVE Depot GnRH agonists are commonly used in the treatment of central precocious puberty (CPP). The triptorelin 11.25 mg 3-month depot, currently used in adult indications, had not previously been evaluated in CPP. METHODS This was a multicenter, open-label, 12 month trial conducted in 64 CPP children (54 girls and 10 boys), treated quarterly. METHODS Children with a clinical onset of pubertal development before the age of 8 years (girls) or 9 years (boys), pubertal response of LH to GnRH > or = 7 IU/l, advanced bone age > 1 year, enlarged uterus (> or = 36 mm) and testosterone level > or = 0.5 ng/ml (boys), were included. Suppression of gonadotropic activation, as determined from serum LH, FSH, estradiol or testosterone, and pubertal signs were assessed at Months 3, 6 and 12. RESULTS GnRH-stimulated peak LH < or = 3 IU/l, the main efficacy criterion, was met in 53 out of 62 (85%), 60 out of 62 (97%) and 56 out of 59 (95%) of the children at Months 3, 6 and 12 respectively. Serum FSH and sex steroids were also significantly reduced, while pubertal development regressed in most patients. Mean residual triptorelin levels were stable from Month 3 through to Month 12. The triptorelin 3-month depot was well tolerated. Severe injection pain was experienced in only one instance. Five girls experienced mild-to-moderate or severe (one girl) withdrawal bleeding. CONCLUSIONS The triptorelin 3-month depot efficiently suppresses the pituitary-gonadal axis and pubertal development in children with CPP. This formulation allows a 3-fold reduction, over the once-a-month depot, in the number of i.m. injections required each year.