From an accident field study carried out in greater Munich area in 1980 a sample of 131 helmeted motorcyclists was investigated with respect to head injury incidence and the material of the shell of the safety helmets. Helmets made of Polycarbonate (PC), Acrylenitrile-Butadiene- Styrole (ABS), and Glass Reinforced Plastic (GRP) were represented in a sufficient number for evaluation. With respect to these shell materials, differences of head injury incidence were found, which in part proved significant. The observed degree of shell damage correlates not necessarily to the sustained head trauma.