The effect of phytase on nutrient digestibility in finishing pigs fed barley-based diet with soybean meal or canola meal as protein source was investigated. Six ileal-cannulated barrows (70 kg initial BW) were fed five diets in a 5 x 5 Latin square design with one added column. The five diets were based on barley-soybean meal (BSBM) or barley-canola meal (BCM) without or with phytase at 500 FTU/kg, and a casein-cornstarch-based diet, which was used to estimate standardised ileal AA digestibilities. No interactions were detected between phytase and diet on any of the response criteria measured except for apparent total tract N digestibility, which was reduced in BSBM diet but not BCM diet by phytase. Phytase increased (p < 0.01) apparent ileal and total tract P digestibility in both BSBM and BCM diets by at least 17 percentage units, and tended (p < 0.10) to increase the apparent ileal digestibilities of histidine, isoleucine, threonine, valine, cysteine, glycine and tyrosine. In conclusion, the effect of phytase in barley-based diets for finishing pigs on all response criteria measured in this study, except apparent total tract N digestibility, was not influenced by protein source.