Hilgenreiner's height (H) and distan.ce (D) as well as AU line length were measured on the pelvic roentgenograms of 90 children (5-12 months old) of which 50 were normal and 40 rachitic. The relationship between AU line and epiphyses of femoral head:was also investigated. We found a highly significant difference between measurements of normal and rachitic children (p<O.OOI). It was seen that, the relations of AU line with epiphyses of femoral head were important among differential diagnosis criteria.