There were studied effects of seven commercial pectinase preparations on the phosphorus release from a wheat-soybean mix feed for broilers. The analyses were carried out using an in vitro method that simulated the digestion process and conditions in individual parts of the bird’s gastrointestinal tract. In the presence of pectinases, there was a statistically significant increase in the amounts of phosphorus released from the feed that correlated well with the viscosimetrically determined overall pectinolytic activity. The determination coefficient of a linear model describing that relationship was 58.62%. The effect analysis of cooperation between the pectinolytic preparations and an ‘A’ phytase, which was simultaneously added to the feed, stated a favourable impact of pectinases on the efficiency of catalytic action of saturating dosages of phytase added. The ability of pectinases to enhance phytate dephosphorylation by exogenous phytase was correlated with the acid phosphatase activity (R² = 93%) accompanying the pectinases. The enhancing effect of pectinolytic preparations on the phytate dephosphorylation was stated even in the presence of a saturating level of phytase and acid phosphatase, however, under such conditions, this effect was negatively correlated (R = – 0,949) with the pectin esterase activity of the preparations investigated. A model of the function y = 3,831+ 0,059/x was the best to describe such a negative relationship between the pectin esterase activity and the amount of phosphorus being released from a feed with the phytase and acid phosphatase dosages at a saturating level. It was quite probable that the high pectin esterase activity in pectinase preparations caused the elimination of Ca²⁺ ions from the reaction environment and stimulated the formation of pectates. The latter ones selectively decreased the efficiency of the phosphorolytic enzymes.