The present paper describes the feasibility of grafting monomeric reactive species onto a plasma gas-activated moving fiber glass surface. The effects of fiber glass surface modifications made in this manner were studied by surface wettability measurements and by mechanical property measurements of composites. Here, it is shown that the on-line grafting of monomeric silane species on a plasma-activated fiber surface can be achieved. It was also demonstrated that, in fact, the fiber surface characteristics changed with monomeric silane grafting and this change was seen in the composite properties when these grafted fibers were used as a reinforcing member in a composite. Demonstration of changes in the composite properties as a result of surface activation followed by grafting is given only to show examples of these effects. The composite properties mentioned in this paper are not to be taken as the optimized maxima for these systems.