Whorwellsdown was a hundred of the English county of Wiltshire, lying in the west of the county to the south of the towns of Bradford on Avon and Melksham and to the north and east of Westbury. An arm of the hundred reached several miles southwards into Salisbury Plain, with a detached portion, a tithing of Tilshead, lying high on the Plain about five miles east of the southern arm of the rest of the hundred.