Myocardial fibrosis in a cardiac allograft may lead to aheart’s structural and functional remodeling and subsequent dysfunction.The frequency of occurrence of alleles and genotypes of the TGFB1 genepolymorphic regions rs1800469, rs1800470, and rs1800471 in heart transplantrecipients and their association with graft myocardial fibrosis were analyzed.Carriers of the CC genotype (p = 0.023, OR = 0.12, 95% CI: 0.017–1.0),and more often the G allele of rs1800471 (p = 0.023, OR = 7.76, 95% CI:1.0–60.20), were found among heart transplant recipients less frequentlythan among healthy individuals. The gene discussed is TGFB1; the disease is Myocardial fibrosis.