Abstract-Plasma copolymers from acrylic acid and allylamine with 1,7-octadiene have been used to deposit conformal functional coatings of approximately 0.01 /xm thickness onto E-glass fibre tows in a semi-continuous process. The adhesion of the fibres to an epoxy resin was studied using the fragmentation test on randomly selected fibres. The optimum concentration of the functional groups (amine or carboxylic acid) required for adhesion has been identified. The stress transfer efficiency has been calculated from the fragment length and debond distributions. This methodology provides a method for determining the ineffective length for the individual combinations of fibre and resin. This new method of quantifying fibre-matrix adhesion would appear to be more discriminating than previous models. The plasma polymers are also effective in protecting the fibres from damage. The Weibull modulus for the distribution of fibre strengths was found to increase after plasma coating. Furthermore, the chemistry of the coating had a major impact with the amine functionality exhibiting the highest Weibull modulus.