We have prospectively assessed the influence of GHR and VDR gene polymorphisms on the response to rhGH therapy in Venezuelan children with growth hormone deficiency (GHD, n=28) and Turner syndrome (TS, n=25). Clinical data during rhGH treatment were compared in GH and TS patients with different genotypes. PCR amplifications were performed to obtain the genotype frequencies of the polymorphisms. Clinical data at the start of treatment and rhGH doses were indistinguishable among patients with GHD or TS with different GHR or VDR genotypes. After the first two years of rhGH treatment, clinical data in both GHD and TS patients were not different according GHR or VDR genotypes. In addition, there was no significant difference among the subjects when both these genotypes were combined. Gene polymorphisms in low penetrance genes do not contribute to the rhGH therapy response in patients with GHD and TS.