The pretreatment of softwood kraft pulps with endo-xylanase expressed from Streptomyces lividans (pIAF18) was shown to have beneficial effects on bleaching with selective oxygen-based bleaching reagents. Optimal biobleaching results were achieved with ozone which exhibited enhanced bleaching selectivity and brightness gains. Enzyme pretreatment also improved brightness and delignification of peracetic acid-bleached pulps. The potential role of xylanase in future commercial applications is discussed.