INTRODUCTION: The natural history of childhood abdominal pain (CAP) and its association with adult irritable bowel syndrome (IBS) remain poorly described. We aim to investigate the characteristics of CAP over the first 11 yr of life and evaluate the association of CAP to IBS at age 26 yr. METHOD: The data were collected from a 1972 birth cohort (Dunedin, NZ) who were re-assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, and 26 yr. IBS was classified according to Manning Criteria, as assessed using symptom data collected at age 26 yr. A history of CAP was established by scrutinizing data for all assessments completed from birth to age 11 yr. Three measures were described: medical service encounters for CAP, parental (mainly maternal) report of stomach pain (frequency over the past year), and a composite measure which included both medical encounters and parent report: three childhood time frames were evaluated - ages 0-7, 7-9, and 9-11 yr. RESULTS: A history of CAP was reported by 18.1% of children. This was typically characterized by CAP on one assessment; complaints over two or more assessment were rare. CAP was slightly more common in females and appeared to peak at age 7-9 yr. IBS at age 26 yr was significantly more common among individuals with a history of CAP between ages 7 and 9 yr compared to those with no such history, as assessed by any history (OR = 1.85; p= 0.02), parental report (OR = 1.82; p= 0.03), and medical service encounters (OR = 3.75; p= 0.03). The association between CAP at age 7-9 yr and adult IBS was not altered by adjustment for sex, socio-economic status, psychiatric disorder at age 26 yr, childhood emotional distress, or mother's score on the Malaise Inventory. CONCLUSIONS: CAP is a common complaint, which can progress to adult IBS in some children.