Fifty-eight children with non-specific back pain lasting for at least 3 months were included in this prospective study. Not included were children with radicular pain or with abnormal findings on clinical examination, radiography, bone scan, computed tomography or magnetic resonance imaging. They were all re-examined after skeletal maturity, on average 7.6 years later. Thirty-one children had pain in the lumbar spine, 20 in the thoracic region and seven over the entire spine. Sixty-two percent of the children were still in pain at follow-up. Female sex and pain in the thoracic region were associated with an increased risk of the pain remaining chronic.