96 gastric mucosal biopsy specimens collected at endoscopy and placed into 3 ml 20% glucose were examined histologically, microscopically (Gram staining), by urease test, and by cultivation. The rate of positive findings ws 62.5% by urease test, 34.4% by cultivation, and 27.0% microscopically. By using simple selective solid media, the number of positive cultivations increased to 58.7%. Positive microbiological findings were established by one of three microbiological methods at a high percentage in gastric ulcers (87.5%) and at the lowest rate in duodenal ulcers (57.1%). Remarkable were the positive findings in 60% of patients with normal endoscopic results. In chronic gastritis the highest positivity rate was established histologically (52.6%). Antibiotics without bismuth preparations were used in the treatment of six patients. Check-up examinations yielded negative histological and microbiological findings only in two patients. We failed to affect the inflammatory activity of the gastric mucosa even when consolidation of the ulcer lesion was achieved.