Abstract: A warning system to alert the rider of a vehicle such as a bicycle or motorcycle that a safety helmet is not being worn when the rider is mounted on the vehicle seat. The warning system includes a helmet holder for storing the helmet when the vehicle is not being used. A first switch is secured to the helmet holder and is adapted to be positioned so that it closes when a helmet is in the holder, and a second switch is secured to the vehicle and is adapted to be positioned so that it closes when a rider is mounted on the vehicle seat. The two switches are electrically connected in such a manner that an alerting device is energized if both switches are closed, indicating that a rider mounted on the vehicle seat is not wearing a safety helmet.