Partial growth hormone (GH) insensitivity can be defined as the clinical and biochemical features of IGF-I deficiency without GH deficiency and in the absence of the dysmorphic features of Laron syndrome. There is good evidence that this form of GH insensitivity exists, both in the context of severe GH resistance, and also in some patients with idiopathic short stature. The series of GH insensitivity patients in the European study shows a spectrum of clinical and biological defects, with several patients at the milder end of the spectrum having normal facies. The report of the presence of heterozygous mutations of the GH receptor in patients with idiopathic short stature has been confirmed by documentation of dominantly inherited mutations in familial short stature. Molecular screening in our unit of a group of 31 children with idiopathic short stature and normal GHBP, failed to identify mutations of the intracellular domain of the GH receptor. Consequently, although partial GH insensitivity is a proven entity, the clinical and biochemical identification of patients with GH resistance should precede molecular analysis. The analysis of individual patients and their families is more likely to reveal mutations, rather than a strategy of blanket molecular screening.