this paper presents data on the tensile performance of hybrid composite materials consisting of pretreated asbestos (chrysotile variety), kevlar fibers, and epoxy resins. asbestos was precoated with a well-adhered film of nylon 6,6, a polymer especially compatible with the epoxy phase. the proposed pretreatment procedure involves serial application to the asbestos of two immiscible solutions of hexamethylenediamine and adipoly chloride, or impregnation in nylon 6,6 solution. combination of the treated asbestos grades with high modulus aramid fibers was followed to investigate the reduction of the asbestos content in only-asbestos-based engineering plastics. the results from the tensile tests revealed composition regions of a possible positive hybrid effect, i.e. a better performance was effected than that encountered in the only-kevlar or only-asbestos-filled composites at the same fiber content. (author abstract) 39 refs