The existence of a relationship between the morphological state of oxynthic gland area of the stomach and the histamine content in the gastric juice was studied. In 86 patients (48 males and 38 females) four groups were formed due to a multiple biopsy pattern: individuals with normal gastric mucosa, with superficial gastritis, with beginning atrophy and with advanced atrophic gastritis. In the basal and maximal stimulated gastric juice the following parameters were used: volume, H+ concentration, acid output, histamine concentration and histamine output. The histamine content was additionally determined also in the plasma. The histamine output and the histamine content of the gastric juice was significantly diminished parallel to the degree of the atrophy of gastric mucosa and parallel to the decrease of the volume and acid output and the increase of the intragastral pH values. In the plasma an increase of the histamine content was observed under similar conditions. A possible relationship is discussed between increased plasma histamine content and increased serum gastrin concentration in cases of advanced atrophic gastric mucosa.