The detection of a genetic organization of common diseases is one of the first key direction in modern medicine. In thyrotoxicosis, identification of genetic predictors, defining remission and the risk of cardiovascular complications is of a great importance. We gave attention to the second of above mentioned aspects. Candidates for genetic prediction are the genes regulated by triiodothyronine and playing a key role in changing of the myocardial contractility and arrhythmogenesis. There are SNPs of the β1-adrenergic receptor (ADRB1) gene among them: polymorphism in the 389 codon (Gly389Arg) and polymorphism in codon 49 (Ser49Gly). The investigation goal was to determine whether the deleterious effects on cardiovascular system of the thyroid hormones excess in people with thyrothoxicosis were modified by polymorphic variants of ADRB1 gene. So we investigated the possible link of these two SNPs with clinicopathologic findings, echocardiographic parameters and the changes during therapy in 165 patients with a thyrotoxicosis caused by Gravesdisease without any nonthyrotoxic cardiovascular disorders. The data analysis demonstrates that both Gly389Arg and Ser49Gly polymorphisms have very moderate influence on the risk of atrial arrhythmias, left ventricular hypertrophy and its type (concentric or eccentric). Genotype Gly389Gly (Gly389Arg polymorphism) or genotype Gly49Gly (Ser49Gly polymorphism) carriers have tendency to the lowest risk of cardiovascular complications during thyrohoxicosis, but no statistically significant effects were revealed.