The authors of this paper have carried out a hypothetical assessment of the difference in the distribution of pressure on the surface of the sole of correctly arched feet, and also of flat feet. They aimed to find out if there are significant differences in the spread of the pressure, and also at which levels of incidence they are highest. The authors carried out the research based on clinical material comprising 133 subjects (266 feet), including 75 females (56.4%) and 58 males (43.6%). The age of the subjects ranged from 10 to 83 years old, with the average age being 41.8 years old. The subjects were divided into three age groups. There were 22 subjects (16.5%) in the first group, aged from 10 to 20 years of age, 37 subjects (27.8%) aged 21 to 40 in the second group, and 74 subjects (55.6%), aged over 40 in the third group. All those included in the research underwent graphic contour testing in accordance with the Clarke method, and pedobarographic testing based on PEL 38. Results obtained suggest that the graphic contour testing is an important element of flat foot diagnosis, and that increased levels of pressure on the soles of flat feet are concentrated in the middle of the foot and below the first bone in the centre of the foot.