Insufficient vascularisation of substitutes in the operative reconstruction of the oesophagus is one of the main causes of the occurrence of anastomotic leaks. In the present study, the blood oxygenation of gastric substitutes for the oesophagus was evaluated before and during the reconstruction. A pulse oximeter was used for the assessment (S&J Medico Teknik AIS, Albertslund, Denmark). Oxygenation in the examined places ranged from 79% to 98%. The values of blood oxygenation in places C1 (fundus of the stomach after the formation of the substitute) and C2 (fundus of the stomach after the formation and stretching of the substitute) were significantly lower than those in analogous places in the stomach before the transformation (C/C1 p