The agonistic analogues of luteinizing hormone releasing hormone were used in the treatment of precocious puberty (pp) in children. 12 children with pp were treated for 6 months with an intranasal LH-RH analogue (C6-C3-C2-naphtyl/D-alanine)-LHRH. The majority of the children had central precocious puberty. Only one child had peripheral pp. Laboratory assessment of estradiol, testosterone, LH and FSH levels revealed that 1,000 micrograms/day of this analogue diminished the hormone levels only in the group of children with central and combined pp. Bone age, pelvic ultrasound examination, sexual development and growth rate were determined pre-, during and after the treatment. The growth velocity decreased and gonadal and sexual characteristic ceased advancing after the LH-RH therapy. Biochemical and hematological studies performed in our children did not show any significant changes during the treatment periods. No adverse effects were noted from the intranasal therapy. We conclude, that intranasal therapy is safe, convenient and effective in pp, but not of peripheral origin.