Hooke Hall, Uckfield, may again become a private home.
The Sisters of the Society of St Margaret are looking to downsize having lived in the premises in the upper part of the High Street since 2006.
Two of the Sisters will continue to live in the town while two more will move to London to work at a nursing home.
The house is now too large for their needs.
The Sisters said they were extremely happy in Uckfield and that it was a lovely town.
No dates have been set for the changes.
Hooke Hall is a Grade II* listed building. It has had a number of uses over the last 60 years including offices, hairdresser, dental surgery and an hotel.
The Trustees of the Society of St Margaret are now seeking formal acknowledgement from the district council that the Hall is a single private dwelling.
The Society of St Margaret is an order of women in the Anglican Church. It was founded in 1855 at Rotherfield.
*The Roman Catholic Sisters of Mercy left their convent (St Michael’s in 2009). The building was demolished and the site is to be redeveloped for homes. History of St Michael’s here