Aldenham is a village and civil parish in Hertfordshire, England, 3.5 miles (5.6 km) north-east of Watford. The civil parish also contains the large and affluent village of Radlett which is 2 miles northeast of the village of Aldenham. The parish was mentioned in the Domesday Book of 1086. In Saxon times the majority of the land was owned by the abbots of Westminster Abbey.
In addition to Radlett, the parish contains the hamlets of Round Bush, Letchmore Heath and Patchetts Green.