Gut microbiota plays an important role in human health and the development of various diseases. We describe the intestinal microbiome of 31 healthy individuals and 29 patients who have hematological malignancies from Belarus. Bacteria that belong to Faecalibacterium, Blautia, Bacteroides, Ruminococcus, Bifidobacterium, Prevotella, Lactobacillus, and Alistipes genera were predominant in the gut of healthy people. Based on the dominant microbiota species, two enterotype-like clusters that are driven by Bacteroides and Blautia, respectively, were identified. A significant decrease in alpha diversity and alterations in the taxonomic composition of the intestinal microbiota were observed in patients with hematological malignancies compared to healthy people. The microbiome of these patients contained a high proportion of Bacteroides, Blautia, Faecalibacterium, Lactobacillus, Prevotella, Alistipes, Enterococcus, Escherichia-Shigella, Ruminococcus gnavus group, Streptococcus, and Roseburia. An increased relative abundance of Bacteroides vulgatus, Ruminococcus torques, Veillonella, Tuzzerella, Sellimonas, and a decreased number of Akkermansia, Coprococcus, Roseburia, Agathobacter, Lachnoclostridium, and Dorea were observed in individuals with hematological malignancies. Generally, the composition of the gut microbiome in patients was more variable than that of healthy individuals, and alterations in the abundance of certain microbial taxa were individually specific.