PURPOSE:There were many controversies whether constitutional delay of growth and puberty(CDGP) is simple varient of normal growth pattern, or one of the cause of growth disturbance induced by the disturbance of growth hormone secrtion or its function. So we studied about the difference in serum peak growth hormone level after insulin, L-dopa provocation test, and serum IGF-I leve between constitutional delay of growth and puberty(CDGP) and familial short stature(FSS). METHODS:Measurement of serum peak growth hormone and insulin like growth factor-I(IGF-I) level after insulin, L-dopa provocation test were performed in 33 children with costitutional delay of growth and puberty (CDGP). Two groups of children with familial short stature (FSS) whose height were below 10 percentile for chronologic age of Korean national height standards were included as control groups. RESULTS: 1)There were no significant difference of serum peak growth hormone level between children with CDGP and children with FSS and these results were similar in both sex. 2)The mean serum IGF-I level of children with CDGP were 125.69+/-4.06 ng/ml(71.53-189.34ng/ml) in male, 157.7+/-3.17ng/ml(81.9-279.2ng/ml) in female. Both results were significantly lower to those of FSS children by chronologic age group because the mean serum IGF-I level of FSS children were 190.19+/-7.97ng/ml (87.64-297.6ng/ml) in male, 205.47+/-15.87ng/ml(61.7-433.1ng/ml) in female. But compared to FSS children by bone age of 72-96 months, there were no significant difference noted because the mean serum IGF-I level of children with FSSwere130.47+/-0.27ng/ml(63.24-198.2ng/ml)inmale,162.35+/-9.43ng/ml(54.9-217.53 ng/ml) in female. CONCLUSIONS:The results of this study showed that the serum peak growth hormone level after insulin, L-dopa provocation test with children of CDGP revealed no significant difference with those of FSS children in both sex. Serum IGF-I level of CDGP children was lower significantly to those of FSS children by chronologic age group, but no much difference with FSS children of bone age group.