Single biopsies of human gastric mucosa from controls and different groups of patients were used for enzymatic cell isolation by pronase and collagenase and subsequent count of parietal and nonparietal cells. This procedure was tested in regard to its validity and delivered the following cell numbers. Total gastric cells/mg wet weight gastric mucosa: normal gastric mucosa [controls (C), n = 95] 31,500 ± (SEM) 1,490, chronic superficial gastritis (GI; n = 49) 36,300 ± 2,770, chronic gastritis with beginning atrophy (GII; n = 36) 44,100 ± 3,050 (p < 0.025), chronic atrophic gastritis (GUI; n = 12) 40,100 ± 5,760, duodenal ulcer (DU; n = 26) 29,340 ± 2,280, gastric ulcer (GU; n = 23) 37,090 ± 3,000, gastric resection according to Billroth II(BII;n = 7)57,480 ± 12,360 (p < 0.005) and Billroth II (BII; n = 12)52,560 ± 6,730 (p < 0.005). Parietal cells/mg wet weight gastric mucosa: 1,910 ± 490 (C), 1,980 ± 140 (GI), 1,700 ± 200 (GII), 1,170 ± 220 (GUI, p < 0.025), 2,580 ± 240 (DU, p < 0.05), 1,690 ± 150 (GU), 1,500 ± 250 (BI), 1,360 ± 320 (BII). Parietal cell concentration (density) did not differ in males and females and did not change with age. The method delivers relevant cell numbers, is suitable to detect qualitative differences and can be used for the interpretation of biochemical studies.