As recycling rates increase and the consumption of graphic papers decrease it becomes more and more difficult to maintain the recycled fibre quality. Also, increasing ash content in the recycled pulp contributes to the strength challenge ahead for the paper and board producers. The fractionation of recycled fibre in this study was made in order to investigate possible routes for upgrading the recycled pulp strength. A recycled pulp for containerboard was fractionated in pilot scale using a pressure screen and hydrocydones. The pulp was first fractionated using a micro-perforated screen basket into a short fraction, with high ash and fines content, and a long fibre fraction. The following hydrocyclone fractionation of the screen short fraction resulted in a fine fraction with fibrillar fines and a coarse fraction containing low bonding fines and fibre fragments together with most of the ash. The short coarse fraction also had a high dirt content. When the screen long fibre fraction was split in the hydrocyclone fractionation, a fine fibre fraction containing good bonding fibres and fines and a coarse fibre fraction with coarse low bonding fibres were obtained. The coarse long fibre fraction was upgraded, to a strength level comparable to the good bonding fine fraction, by refining with an energy input of only 24 kWh/t calculated on the whole pulp. This selective refining of the coarse long fibre fraction resulted in an improvement of the pulp strength by 20 % when the pulp fractions were mixed back together in the same proportion as they had been separated. Further strength was gained when the low bonding short coarse fraction with high ash content was removed. This study showed that a recycled pulp can be upgraded by selective and appropriate treatment of the different streams, with different properties, produced in a fractionation process.