A commercially available microbial phytase was investigated with the aim of firstly, determining its effectiveness in releasing phosphate from phytate and secondly, investigating the possible binding of supplemented amino acids to phytate and the effectiveness of microbial phytase in releasing bound amino acids. Feedstuffs with added synthetic amino acids were incubated in the presence or absence of microbial phytase and the resulting concentrations of free phosphate and free amino acids were determined. The mean dephosphorylation of phytate over all feedstuffs and reaction conditions used was 0.40. Dephosphorylation ranged from 0 for wheat pollard to 0.84 for cottonseed meal depending on the feedstuff and the reactions conditions used. Incubation in the absence and presence of microbial phytase resulted in a recovery of supplemented amino acids of between 0.37 to 1.15 (mean = 0.84) and 0.49 to 1.17 (mean = 0.89), respectively, depending on the amino acid, feedstuff and reaction conditions employed.