The population prevalence of congenital hypertrophic pyloric stenosis in Donetsk region in the course of 11 years (1989-1999) has been descriptively studied. Its frequency is 0.73:1000 or 1:1370 newborn infants annual with range of 0.54 to 1.01:1000. It is somewhat lower than that of more wide spread congenital diseases: labial cleft and hemochromatoses. Pyloric stenosis is detected in 42 of 43 populations of Donetsk region. There is a population nonuniformity of the case rate: from 0.19 to 1.9:1000 newborn infants, that the authors are inclined to explain by dissimilarity of a gene pool in the populations due to random migration of the population.