Background: This article investigated the prevalence of peanut allergy in three cohorts of children born in the same geographical location, Isle of Wight, UK and seeks to determine whether the prevalence of peanut allergy has changed between 1994 and 2004. Methods: Three cohorts of children (age 3-4 years) born on the Isle of Wight, were assessed for peanut allergy and the outcomes compared: Cohort A: Born in 1989; reviewed at 4 years of age (n = 2181). Cohort B: Born between 1994 and 1996; reviewed between 3 and 4 years of age (n = 1273). Cohort C: Born between 2001 and 2002; reviewed at 3 years of age (n = 891). Results: Peanut sensitization increased significantly from 1.3% in Cohort A to 3.3% (P = 0.003) in Cohort B before falling back to 2.0% in Cohort C (P = 0.145). Similarly, clinical peanut allergy increased significantly from 0.5% in Cohort A to 1.4% (P = 0.023) in Cohort B, with a subsequent fall to 1.2% in Cohort C (P = 0.850). Conclusions: Our data from three cohorts of 3- to 4-year-old children born in the same geographical area shows that peanut allergy prevalence has changed over time. Peanut sensitization and reported allergy in children born in 1994-1996 increased from 1989 but seems to have stabilized or slightly decreased since the late 1990s, although not significant.