The final height of patients treated with growth hormone for isolated growth hormone deficiency has, up to now, been subnormal, with a mean below -2 SD in the series reported, an insufficient height at the onset of puberty and a more or less accelerated bone maturation during puberty being two important factors of the poor results. A long-acting analogue of gonadoliberin, Trp6-GnRH, has been given to GH-treated patients with isolated growth hormone deficiency at the time they reached pubertal stage 2, in combination with unchanged doses of GH, for one year in 11 and for two years in 7 of them. It resulted in an increase in the height age/bone age ratio and a reduction of the height insufficiency for bone age. The increase was slight but significant after one year, and fair after two years, in spite of reduced annual growth rate. Post-analogue follow-up in 5 patients with continued GH treatment showed a good development of growth and of puberty. It is concluded that combination of the long-acting Trp6-GnRH analogue and GH for 1-2 years in patients with isolated growth hormone deficiency whose puberty starts with a very insufficient height may be an appropriate way to improve their growth parameters. Studies with increased doses of GH or increased frequency of injections could help to optimize the results. Several years of follow-up are needed for demonstrating the results on final height.