<i>Background/Aims:</i> Expression of the human growth hormone (GH) gene <i>(GH1) </i>is regulated by a locus control region (LCR) and the highly polymorphic <i>GH1 </i>promoter. We analyzed <i>GH1 </i>LCR/promoter single nucleotide polymorphisms (SNPs) in patients with isolated growth hormone deficiency (IGHD) in relation to clinical data. <i>Methods:</i> We directly sequenced the <i>GH1 </i>LCR/promoter of 62 Dutch IGHD patients without mutations or deletions in <i>GH1 </i>or <i>GHRHR</i> and of 72 controls with normal height. We related <i>GH1 </i>LCR/promoter SNPs to height, serum insulin-like growth factor 1 (IGF-I) levels and response to GH treatment. <i>Results:</i> In IGHD patients, promoter SNPs 6, 8 and 9 were associated with height and IGF-1 levels. In controls, SNPs 6 and 11 were associated with height. Homozygosity for the minor allele of SNP 9, associated with lower IGF-I levels in patients, was significantly more frequent among patients than among controls. Genotypes based on SNPs 6, 8, 9 and 11 explained 10.8% of IGF-I SDS variation in IGHD patients and 15.9% of height SDS variation in controls. <i>Conclusion:</i><i>GH1</i> Promoter SNPs 6, 8 and 9 were associated with height and IGF-1 levels among patients, and SNPs 6 and 11 with height in controls.