We investigated the prognosis of low-back pain and the association of clinical symptoms and anatomic findings among young athletes. Consecutive patients, aged between 12 and 18 years, who had low-back pain that had interfered with their training for at least 4 weeks were included in the case series. All the patients participated in a standardized interview and clinical examination, and plain radiographs and magnetic resonance images were also obtained. Most patients also participated in technetium bone scan examination. In 15 out of 19 subjects there were anatomic abnormalities that corresponded with the location and type of clinical symptoms. Twelve subjects had changes in the disk-vertebral end plate complex and eight had a positive bone scan indicative of posterior vertebral arch stress reaction. Six out of eight boys and two out of 11 girls had stress reaction (P = 0.043). Restriction of painful activities was recommended to all subjects, restriction of activities and the use of a dynamic low-back brace for the first 3 months was recommended to patients with posterior vertebral arch stress reaction. The self-reported intensity of low-back pain (scale 0-100) among all the patients was 69 +/- 16 (mean +/- SD) at baseline and 18 +/- 21 at the 1-year follow-up (P < 0.0001). In conclusion, the reasons for prolonged back pain among young athletes are usually established by imaging studies. A knowledge of anatomic abnormalities may help in tailoring training programmes and avoiding the progression of changes during growth. Simple restriction of painful activities usually leads to good recovery.