Motorcyclists using the Wicklow Gap between Laragh and Hollywood (R756) are being advised to drive with caution following a number of incidents during the week.
A silver car has been obstructing motorcycles in a dangerous manner.
One motorcyclist described how the car pulled out in front of him and swayed from side to side, preventing him from overtaking.
Incidents of a motorbike terrorist were reported along the same stretch of road during July 2015 involving a silver Seat Leon, though it is not known if it is the same car.
The R756 is one of the most popular routes in Ireland for motorcyclists.
Drivers are being advised to report incidents to the Gardai.