Thirty-nine 15-year-old children with low-back pain (LBP) and 39 asymptomatic control children were selected from a population of 1,503 children of the same age for a magnetic resonance imaging study of the lumbar spine. Subjects with LBP were matched with control subjects by age, sex, and school class. Disk degeneration (DD) was present in 15 (38%) of the children with LBP and in 10 (26%) of the control subjects. Lumbar degeneration was most frequently associated with disk protrusion and Scheuermann-type changes. Of assessed structural abnormalities (disk protrusion, Scheuermann-type changes, transitional vertebra, and disk space narrowing), only disk protrusion was more common in children of the LBP group than in control subjects. The authors conclude that DD is a frequent finding among children with LBP at the age of 15 years. Asymptomatic (possibly physiologic) DD also is frequently found in children of this age. Whether DD associated with structural changes predisposes to low-back disorders can be confirmed only by means of a longitudinal follow-up study.