Glutathione S-transferase (GST) plays a key role in detoxification of xenobiotics and consequently polymorphisms of GST gene may determine susceptibility to several types of metabolic disorders and endue free radicals elimination. There is still no clear evidence of GSTM1 and GSTT1 genes association with gastroesophageal reflux disease (GERD) complication by diabetes mellitus type 2 (DM2). Therefore, the aim of the study is to establish the difference in null GSTM1 and GSTT1 genes polymorphisms between GERD patients with and without diabetes in Northern Bukovina (Western Ukraine).