To learn about children's ability to estimate the duration of an event many days after it occurred, 6–12-year-old children were asked to judge the amount of time (range 5–45 minutes) they spent in the treatment room as part of a paediatric visit. Judgements were made 1 week or 1 month after the visit occurred. Children showed an average error of about 13 minutes. Retention interval did not significantly affect estimates. Other judgements of the length of the interview itself (mean length 8 minutes) provided what may be the first data on children's ability to make immediate retrospective duration estimates. The results also include information about children's capacity to judge how long ago they visited the clinic. Copyright © 2009 John Wiley & Sons, Ltd.