GH is a dominant factor in determining growth during childhood. Hence, the assessment of GH secretion is of major importance in the diagnosis of growth disorders. Since GH is secreted in a pulsatile fashion, a truly accurate production rate can only be calculated by using very frequent or continuous blood sampling over a 24-hour period. Several standard provocative tests have been established to evaluate GH secretory status. They remain the cornerstone in the assessment. Recent data have shown the existence of a wide spectrum of GH secretory disturbances ranging from severe GH deficiency to partial insufficiency and neurosecretory dysfunction. There is no well-defined cut-off point at which a particular child can be regarded as GH insufficient or sufficient for optimal growth. In clinical practice, the assessment of GH secretion starts with the careful analysis of the growth chart and height velocity. Careful clinical examination of the patient is essential for the proper diagnosis, and to exclude diseases influencing GH secretion. Additional biochemical tests may be required for the differential diagnosis. Thus, assessment of GH secretion in children requires auxological, clinical and biochemical data. GH insufficiency is documented by additional testing of pituitary secretory capacity either by standard provocative tests, by studying 24-hour GH profile or by measuring 24-hour production rate. The main goal is to detect those children who will benefit from treatment with hGH. The final assessment might consist in the response of growth velocity to exogenous hGH.