A bench-scale continuous fibre treatment line has been built to modify polyethylene fibre surfaces using UV radiation-induced grafting. It is shown that grafting does indeed take place and that the grafts adhere well to the resin. Single-fibre pullout behaviour, interlaminar shear strength, and flexural behaviour were observed to improve considerably. The loss of tensile properties due to treatment was investigated and found to be small in the range of useful treatments. The interlaminar shear strength of the UV-treated fibre is as high as 38 MPa (5.5 ksi) as compared with the untreated fibre value of 10 MPa (1.5 ksi). The most important process parameters are identified and trends established.