We propose to treat pubertal children with extreme short stature with a long-acting analog of luteinizing hormone-releasing hormone (D-Trp6-Pro9-NEt-LHRHa). The goal of LHRHa treatment in these children is to halt the normal progression into puberty and thereby delay epiphyseal fusion. We postulate that delay of puberty will prolong pre-pubertal growth prior to the pubertal spurt and subsequent epiphyseal fusion, and thus will enhance ultimate height. This study will test this hypothesis through a double-blind, randomized comparison of the effect of LHRHa and placebo on final adult height. Patients will be treated with LHRHa or placebo for 4 years, and will then be followed until they have completed puberty and have stopped growing.