In a longitudinal study, age at menarche for Swedish girls was recorded by school nurses. Some four years after the event the girls were asked to recall the date. The correlation between actual and recalled age at menarche for 339 girls was r = 0-81 +/- 0-05. 63 per cent of the girls recalled the date within +/- 3 months. It is concluded that recalled age is too inaccurate for most purposes.