Two batches of a commercial double-low rapeseed meal (RSM) were separated into two fractions on sieves with a mesh diameter of 0.5 mm. In the higher-protein fractions (HP-RSM), which constituted about 35% of regular RSM (R-RSM), the crude protein level increased by 16% in the first batch and by 11% in the second, while crude fibre decreased by 19 and 14%, respectively. The glucosinolate (GLS) content rose from 15.5 to 16.7 µM/g defatted DM in the first batch and from 10 to 11.9 uM/g in the second. In both batches HP-fractions contained less methionine and cystine, while more histidine and phenylalanine than R-RSM. Two experiments were carried out, each on 1190 commercial broilers allocated to 14 pens on litter. In both experiments the birds were fed starter diets without RSM for the first three weeks. In the grower and finisher diets soyabean meal (SBM) was substituted, partially or totally, by R-RSM or HP-RSM. In Experiment 1 control broilers were significantly (P<0.01) heavier than those from the experimental groups, and birds receiving R-RSM were heavier (P<0.05) on day 48 of life than those given HP-RSM. In Experiment 2 there were no significant differences between the weight of birds receiving SBM or RSM in the diets, however, those given HP-RSM were slightly lighter. In Experiment 2 chickens fed RSM had larger livers (P<0.05) and thyroids (P<0.01) than the control birds. In both experiments feed conversion efficiency in RSM- fed groups was poorer than in control one, even when the available lysine level was not lower than in the control diet.