Helmets worn by motorcyclists decrease head injuries and the likelihood of being killed in a crash by about 30 percent. From 1968 to 1977, Texas had a comprehensive motorcycle helmet use law, which was estimated to have saved 650 lives. But the law was amended in 1977 to apply only to motorcycle operators and passengers under age 18. In September 1989, a new law was passed that required helmets for all motorcycle operators and passengers. Observations of helmet use were conducted before and after the law took effect in 18 Texas cities using a survey design providing a cross-section of urban and suburban traffic across the State. The surveys indicated that helmet use increased from less than 50 percent just before the law to 90 percent immediately after, and it increased further to more than 95 percent 2 months later. These results confirm the unique effectiveness of comprehensive helmet use laws in applying the proven public health benefits of helmets to the reduction of motorcycle injuries and deaths.