A woman walking her dog in Twyford Woods was approached by a man who made inappropriate comments to her, say police.
The incident happened on Tuesday afternoon, described by the woman as non-aggressive nor intimidating.
The man was white, aged around 30 years old, of a medium build, wearing a green sweatshirt with white wording on it.
PCSO Stuart Bowden, of the Grantham Rural South neighbourhood policing team, asks anyone with a similar experience to report it on the non-emergency 101 number, quoting incident number 250 of January 27.
Twyford Woods is off the A151, off the A1 towards Corby Glen.