**Abstract**

The study aimed to assess the link between procalcitonin (PCT) and gut dysbiosis in patients with nonalcoholic fatty liver disease (NAFLD). A total of 125 research participants, 100 patients with NAFLD (59% women and 41% men) age between 43 and 84 years and 25 healthy controls, joined this observational study. Patients were consecutively enrolled into two groups: 50 with gut dysbiosis and 50 without gut dysbiosis, after several conditions have been ruled out. Patients from dysbiotic group displayed significantly lesser use of biguanides and statins and elevation of fatty liver index (FLI), PCT, C-reactive protein (CRP), and alanine aminotransferase (ALT). Their gut microbiome was characterized by *Bacteroides* and *Prevotella* sp. dominant enterotype (74%) and by *Ruminococcus* sp. in only 26% of cases. The decrease of H index of biodiversity was observed in 64% of patients as well as of *Firmicutes/Bacteroidetes* (F/B) ratio and *Akkermansia muciniphila* in 60%. The increase of lipopolysaccharide positive bacteria was noted in 62% of patients. PCT strongly correlated with the level of CRP and ALT as well as to stool's H index of biodiversity and F/B ratio. Dysbiotic patients with NAFLD exhibited significant elevation of PCT that correlated well with the H index of stool's microbiota biodiversity, F/B ratio, CRP level, and severity of cytolytic syndrome.

**Keywords:** nonalcoholic fatty liver disease, procalcitonin, gut dysbiosis, gut microbiota, C-reactive protein
