Idiopathic short stature represents a group of conditions that are not definable by current biochemical criteria but usually respond to GH therapy. Natural-history studies confirm adult height will be short in untreated ISS individuals. Children and adults with short stature have disadvantages compared with their peers. The evidence for benefit from treatment of children with idiopathic short stature is strong. Numerous studies, now including a placebo-controlled study, have demonstrated the positive effect of GH treatment on final height. The effect of GH treatment is quantitatively similar to results seen in other non-GH-deficient conditions. Although currently very expensive, rhGH treatment is relatively safe. GH treatment of children with idiopathic short 'stature should not be withheld because of our inability to explain the etiology or because of the inadequacy of our current diagnostic tests. Continued efforts to delineate specific causes of poor growth in ISS individuals may result in our being able to predict subsets of individuals who will respond well to GH and subgroups who may be considered for other treatments, such as IGF-1 or a combination of IGF-1 and IGFBP-3.