Aldenham is a village and civil parish in the borough of Hertsmere in Hertfordshire, England. The parish includes Radlett and Letchmore Heath as well as Aldenham village itself. The village of Aldenham lies 3.5 miles north-east of Watford and 2 miles southwest of Radlett. Aldenham was mentioned in the Domesday Book of 1086, and is one of Hertsmere's 14 conservation areas.