Chicken growth hormone (cGH), a polypeptyde hormone synthesized in and secreted by pituitary gland, is involved in a variety of physiological functions such as growth, body composition, egg production, aging and reproduction. Two breeds of chickens selected for high and low incidence of scoliosis, were analysed for polymorphisms in the growth hormone gene (GH). The polymorphism of GH gene (PCR-RFLP) was analysed in 30 chickens each breed, Rhode Island Red and Sussex. It was observed five RFLPs in GH gene, three at MspI sites in the intron 1 of cGH gene and two MspI sites in the intron 4 of cGH gene. The selection for axial skeleton malformation appears to have affected the frequency of GH alleles. It was found differences in allelic distribution between the affected (H) and unaffected (L) lines. Whereas none of the alleles was observed as specific to H or L lines for both breeds. The experimental material examined constitutes a valuable source for identification of real genes causing skeletal defects.