PROTOCOL OUTLINE: This is a randomized, double blind study. Patients are randomized to receive leuprolide acetate or gonadotropin releasing hormone (GnRH) first, then cross over to receive the other test.

Patients receive one subcutaneous injection of leuprolide acetate or GnRH, then have blood samples drawn periodically. One month later, patients receive the other test.

Another cohort of patients are randomized to receive leuprolide acetate once daily on days 0, 4, and 8, or days 0, 5, and 10.

Patients are followed for up to 2 years.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics--

• Prepubertal children with constitutionally delayed puberty At least 2 years retardation of bone age Spontaneously progress into puberty within 1 year Boys: Testes long diameter 2.5-3.5 cm and plasma testosterone 40-300 ng/dL Girls: Breast development, but premenarcheal OR Hypogonadotropinism Delayed onset of pubertal milestones associated with anterior panhypopituitarism OR Kallman's syndrome No spontaneous progression into puberty within 2 years after 6 months replacement sex steroid treatment

--Prior/Concurrent Therapy--

• At least 2 months since prior sex hormone treatment

--Patient Characteristics--

• Age: 14-18 for children with hypogonadotropinism 9-13 for normal children
• Other: No chronic systemic disease No metabolic disease No endocrine disease No growth hormone deficiency