Twenty-one children with early puberty have been evaluated to determine adequate dosage of depot leuprolide acetate. The minimal dosage of depot leuprolide acetate required, using intervals of 1.5 mg or less when given every 28 days, was determined. This dosage, as determined by suppression of gonadotropin responses to GnRH stimulation, was 4.14 +/- 1.33 mg (mean +/- SD) and 0.15 +/- 0.07 mg/kg.28 days. The dosage correlates with bone age and pubertal stage and is larger among patients with more advanced puberty. Five patients required a larger dosage from 5-10 months after initial suppression. Therefore, to monitor suppression, GnRH testing should be repeated at least at 6-month intervals. Samples 20 and 40 min after GnRH stimulation are sufficient to indicate adequacy of treatment, so an abbreviated test could be used.