Various conventional roentgenographic methods have been proposed to determine the severity of chronic slipped capital femoral epiphysis (SCFE) on the sagittal plane, with some maintaining that computed tomography (CT) is more accurate and reproduces better than roentgenography. We used a modified Dunlap's technique and angular measurement to determine slip severity. Three orthopaedists obtained data from roentgenograms and CT of 20 hips with chronic SCFE. Statistical analysis showed concordance between our method and the measurements and reproducibility produced with CT. The results suggest that our method is as effective as and less expensive than CT.