State law currently requires all motorcycle riders to wear helmets. This year's version of the bill would make helmets optional for those who are at least 21.

Those who support making helmets optional say that the helmet requirement intrudes on civil liberties. Critics say repealing the helmet law will lead to more serious accidents and injuries and create more health care expenses for everyone.

Federal traffic data shows that 390 people died in motorcycle accidents in Missouri from 2002 to 2006.