A method was presented for the medical management of low back injury which proved valuable in reducing the incidence of injury and resulting period of disability. Workers involved in uranium mining were divided into two presenting groups. The first group contained men with conditions which do not contribute to an increase in the frequency of injury or to prolongation of recovery. The second group contained conditions which contribute to increased injury, to prolongation of healing, and to an increase in frequency and degree of permanent disability. Based on analyses of several cases, those conditions which are called noncontributing factors include the normal back, or the back with no appreciable lesion, the back which has bilateral sacralization of the sixth lumbar vertebra, the ordinary spina bifida occulta not extending completely through the body of the sacrum, centers of ossification in the lateral films on the margins of the bodies, mild to moderate Schmorl's nodes, and mild to moderate scoliosis. Conditions which have contributed to the severity and frequency of injury include a thinning of the intervertebral space with or without backward displacement of the proximal vertebra on the distal vertebra, spondylolisthesis, generalized exostosis or a hypertrophic type arthritis greater than a mild or minimal degree, and unilateral sacralization of either a fifth or sixth lumbar vertebra, old health fractures, and fusions and results of former disc surgery. Patients who suffered a back injury and had a contributing factor lost an average of 131.61 days per employee. Those without contributing factors lost an average of 35.9 days. The author concludes that preemployment roentgenograms of the lumbosacral area can be used to classify workers as to whether they have anomalies which would be contributory to injury.