Thirty-five states repealed or altered mandatory motorcycle helmet legislation since May 1976. In-depth evaluation of the impact of the change has been reported from four states. The results reveal significant decreases in helmet usage and significant increases in head injury and deaths. In one state (Kansas) there was also an increase in the accident rate. Evaluation of the financial impact reveals up to 200% increase in medical costs and a significant increase in days of disability. Repeal of mandatory helmet legislation is extremely costly in any parameter measured.