The dent resistance of aluminum and steel autobody panels has been studied under controlled laboratory conditions and by field observations and measurements of actual hailstone damage. Analysis of the results shows that very nearly the same response occurred in the lighter weight aluminum components as occurred in the steel panels.The autobody components were all 1977 model year production panels. Laboratory testing included four steel and four aluminum hoods, both painted and unpainted. The hailstone damaged components included a steel hood, aluminum doors and an aluminum fender. The aluminum and steel panels were damaged in the same hailstorm during May 1977.The analysis of denting resistance presented in this paper is based on insight and experience gained from a four-year cooperative program of Reynolds Research and several automobile companies. The results given here supplement previously published laboratory data and confirm the conclusion that lighter weight aluminum autobody panels can be designed to give at least comparable, if not better, dent resistance than conventionally used steel panels, and at a weight savings of 50 percent.