The Rhondda Fun Run will take place this weekend - on Sunday, July 6 - with various road closures in place.
The 10-mile event, organised by LR Sporting Events, returned in 2013 after an absence of 10 years.
The Rhondda Fun Run will start at 9am at Rhondda Sports Centre, Gelligaled Park, Ystrad, with the course taking competitors through Treorchy, Ton Pentre and the half-way point at Gelli Industrial Estate.
It will then continue pass Llwynypia Hospital and on towards Trealaw before returning back to Rhondda Sports Centre.
Motorists are advised that delays may be possible for the duration of the event.
The Rhondda Fun Run is a privately-organised event which is non-competitive and open to all runners of 10 years and over. All under-16s will need to be accompanied by an adult.