Radiograms and case histories of 654 randomized patients with 976 arthrotic hip joints have been reviewed in an attempt to make an etiological diagnosis. 98.3% of the patients and 98.8% of arthrotic hips, respectively, could be determined as to their underlying praearthrotic deformities according to Hackenbroch sen. The respective mean value gained from 6556 patients published in the world literature is 74.2% with marked individual variations. Most frequent praearthrotic condition was found to be congenital hip dislocation, followed by epiphyseolysis capitis femoris juvenilis, trauma, coxitis, M. Perthes, coxa vara, protrusio acetabuli, idiopathic femoral head necrosis, ankylosing spondylitis and several more rare basic conditions.--The most important reasons for differing results are discussed: Specific composition of clinic cases, completeness of documentation, experience of the reviewer and considerable space for personal interpretation. Relevant epidemiological data are also mentioned; they are in agreement with clinical experience and published data.--Finally it is stated that present diagnostic methods are not able to detect all praearthrotic conditions.