Under conditions simulating intestinal digestion in broilers, phytase B was found to free myo-inositol from low non-phytate phosphorus maize–soyabean meal-based and wheat–soyabean meal-based diets, whereas both 3- and 6-phytases A accelerated myo-inositol release only in the presence of phytase B. In the feeding experiment, myo-inositol at 1 g · kg^–1 increased the feed intake and body weight gain of broilers fed both types of feeds. Phytase B at 1300 acid phosphatase units (AcPU) · kg^–1 enhanced feed consumption, body weight gain, and tibia mineralization, whereas phytase B mixed with 6-phytase A at 500 phytase units (FTU) · kg^–1 produced further enhancements in performance and bone mineralization. After 6 weeks, broilers fed the maize-based diets supplemented with both phytase B and 6-phytase A had increased serum concentrations of triglycerides and HDL-cholesterol, as well as an enhanced HDL/total cholesterol ratio. The increases in this ratio cannot be attributed to the release of phosphorus or to the generation of myo-inositol by the supplemented enzymes, but can only be explained as effects of intermediate products of phytate dephosphorylation.