It is well known that height at the onset of puberty is closely related to final height. To improve final height of short children who enter puberty at short stature, twenty-one short boys and six short girls were treated with a combination of GH and GnRH analog. The boys started the combination treatment at a mean age of 12.0 years when their mean height was 128.5 cm (-2.74 SD) and the girls at a mean age of 10.68 years when their mean height was 126.4 cm (-2.23 SD). The boys discontinued GnRH at a mean age of 16.88 years after a mean treatment period of 4.89 years when their height was 153.7 cm (-2.75 SD), and the girls at a mean age of 13.89 years after a mean treatment period of 3.20 years when their height was 143.3 cm (-1.94 SD). Bone age maturation significantly decelerated during the combination treatment. Bone age rarely exceeded 14 years in boys and did not exceed 13 years in girls. Bone age maturation during combination treatment decelerated after bone age 12 years in boys and 10.5 years in girls. On average, bone age matured at a mean rate of 0.48 years a year in boys and 0.56 years a year in girls during the combination treatment. During the combination treatment, height velocity did not decelerate rapidly and remained at 3-5 cm/year for a longer duration because of the bone age deceleration, although a definite pubertal growth spurt was not observed. As a consequence, the mean projected height SDS for bone age increased 1.50 (+/- 0.76) SD in boys and 1.24 (+/- 0.49) SD during the combination treatment. Although most of the patients have not yet reached their final height, combined GnRH analog and GH treatment should increase the pubertal height gain and the adult height in short children who enter puberty early for height, when the post-GST growth is taken into account. The combination treatment seems more effective in boys than in girls. This improvement is attributed to the lengthening of the treatment period by slower bone maturation and maintained growth velocity.