The evaluation of the clinical features of chronic atrophic gastritis (CAG) found the presence of the main symptoms in all patients in all 3 study groups. The frequency and severity of symptoms were also similar in patients in all study groups. The analysis of the number of mentioned manifestations revealed that 3-5 symptoms indicated all (100.0%) patients with CAG and gastric mucosal epithelial dysplasia, compared to 92.1% patients with CAG without gastric intestinal metaplasia (IM) and without dysplasia (p <0.05) and with 90.2% of patients with CAG and IM (p <0.05). Therefore, patients with CAG and dysplasia have a more critical condition with a more severe clinical picture and a higher frequency of inefficiency of the treatment administered. The diagnosis of gastric mucosal atrophy (GMA) based on serological parameters depends on the morphological type of gastric lesion: it is reduced in patients with CAG without IM and without dysplasia, and increases simultaneously with the morphological worsening of CAG. Serological determination of GMA is important for the non-invasive diagnosis and prognosis of CAG with IM and / or CAG with dysplasia, conditions that represent significant risk factors for the development of gastric cancer. The study of the relationship between morphological condition and functional activity of the gastric mucosa by determining the concentration of serological markers found a statistically significant reduction in mean pepsinogen-I and pepsinogen-I / II and a statistically significant increase in serum nitric oxide values and nitric oxide in gastric juice concomitantly with morphological worsening of CAG.