OBJECTIVE Longitudinal studies of juvenile migraine are very few. We investigated the prevalence and evolution over 5 years of migraine without aura (MWOA) and migraineous disorder (MD) in an adolescent population. METHODS Sixty-four subjects (34 girls and 30 boys, mean age 17.3+/-1.1 years) out of 80 selected in our 1989 epidemiological survey were included in the study. The diagnostic criteria of the International Headache Society were used in both studies. RESULTS Thirty-two of 64 subjects (50%) had MWAO, 18 (28.1%) had MD, and 14 (21.9%) had headache not classifiable (HnC). Our results show that MWOA persisted in 56.2%, converted to MD or HnC in 9.4% and 3.1% of cases, respectively, changed to episodic tension-type headache (ETTH) in 12.5%, and remitted in 18.8%. MD persisted in 11.1%, converted to MWOA or HnC in 27.8% and 5.5% of cases, respectively, changed to ETTH in 11.1%, and remitted in 44.5%. HnC persisted in 14.3%, converted to MD or MWOA in 21.4% and 14.3% of cases, respectively, changed to ETTH in 14.3%, and remitted in 35.7%. CONCLUSIONS Our data indicate that juvenile-onset MWOA and MD may change in character over time, generally with a favorable prognosis.