This paper concerns the determination of the share of fungi of the Saccharomyces genus in the mycobiota of the gastrointestinal tract of patients with colorectal cancer. The biological material were fungi isolated from the mouth, oesophagus, duodenum, stomach, large intestine and anus of 92 patients with colorectal cancer. They were subjected to standard mycological diagnostic testing. The analysis was only carried out on isolates containing fungi of the Saccharomyces genus. In 140 isolates (24.5% of all positive results), the species S. cerevisiae (68.5%), S. fragilis (5.71%), S. italicus (11.43%), S. ludwigii (8.60%) and S. rouxii (5.76%) were found, which occurred individually or were accompanied species of the Candida, Trichosporon, and Rhodotorula genera. Most isolates were obtained from the large intestine and anus, and the least from the stomach. It follows from the comparison of the obtained results with those of previous studies into the occurrence of fungi of the Saccharomyces genus in various segments of the gastrointestinal tract, that their prevalence in the gastrointestinal tract is gradually increasing.