The river rises near
Dunlavin,
County Wicklow in the townland of Tober. It then runs south-west and forms part of the
County Wicklow/Kildare border. The Greese continues west past
Killeen Cormac (formerly
capella de Gris, from which the river takes its name). It is bridged by the
R448 road at Moyleabbey, County Kildare. It meets a tributary in
Crookstown and passes under the
R415, then flows southward through
Ballitore. The Greese flows south-southwest, crossing under the
M9, through Kilkea Golf Club and past
Kilkea Castle, passing under the
Dublin–Waterford railway line at Newtownpilsworth/Dunmanoge and draining into the
River Barrow in the Jerusalem townland, Painestown downstream of Maganey Lock (this last stretch forms part of the
County Carlow/Kildare border). ==Wildlife==