Microsatellite polymorphism (CA)n within the first intron of the interferon- gamma gene was assessed in 160 recipients of an allogeneic hematopoietic stem cell transplant (HSCT). IFN- gamma 3/3 was found to be associated with an increased risk of chronic graft-versus-host disease (GvHD) (11/27 vs 26/133, p=0.02). Forward logistic regression analysis confirmed the role of IFN-gamma 3/3 genotype as one of the risk factors for manifestation of chronic GvHD (OR=3.180, p=0.018) together with previous acute GvHD (OR=2.752, p=0.024), cyclosporine A monotherapy (OR=2.607, p=0.029) and malignant disorders (OR=4.371, p=0.032).