Spinal posture and the resultant changes during the entire pubertal growth period have not been reported previously. No cohort study has focused on the development of spinal posture during both the ascending and the descending phase of peak growth of the spine. The growth and development of a population-based cohort of 1060 children was followed up for a period of 11 years. The children were examined 5 times, at the ages of 11, 12, 13, 14 and 22 years. A total of 430 subjects participated in the final examination. Sagittal spinal profiles were determined using spinal pantography by the same physician throughout the study. Thoracic kyphosis was more prominent in males at all examinations. The increasing tendency towards thoracic kyphosis continued in men, but not in women. The degree of lumbar lordosis was constant during puberty and young adulthood. Women were more lordotic at all ages. Thoracic hyperkyphosis of > or =45 degrees was as prevalent in boys as girls at 14 years, but significantly (P<0.0001) more prevalent in men (9.6%) than in women (0.9%) at 22 years. The degree of mean thoracic kyphosis and the prevalence of hyperkyphosis increased in men during the descending phase of peak growth of the spine, but decreased in women.