A 47-year-old woman was sexually assaulted in a Berkshire wood by a man who approached her from behind.
Thames Valley Police said she was walking in High Woods, Woodley, between 14:00 and 14:10 BST on Friday.
A man walked up behind her, touched her inappropriately and fled in the direction of Kingfisher Drive. The woman shouted at him to stop.
The suspect is white, slim, between 5ft 3in and 6ft, with dark hair around the side of his head and bald on top.
He was wearing a royal blue polo shirt with a mustard-coloured line around the collar.
PC Zoe Eele said it was "a very distressing incident for the victim".