The availability of phytate phosphorus (P) was determined in hens fed a maize-soybean meal diet. The availability of phytate P was higher in 47?wk?old hens (53%) than in 20?wk?old hens (24%). The excreta of older hens contained significantly less phytateP (3.1 mg/g DM) than that of younger hens (4.5 mg/g DM). Specific activity (per g) in the stomach, intestinal mucosa and caeca was higher in 47-wk-old hens than in 20-wk-old hens. A relatively high total phytase activity was found in the caeca of both young (347 micromol/h) and old (632 micromol/h) hens compared to that in other digestive segments, with little activity in the stomach (47 and 102 micromol/h, respectively), and intermediate in the small intestine (226 and 264 micromol/h, respectively).