Phytases (myo-inositol hexakisphosphate phosphohydrolases) are produced in plants and microorganisms, particularly in fungi. Phytases produced by Aspergillus niger are active at acidic conditions. The enzymes have found wide application as supplement for animal feed. In this study, DNA ftagments encoding mature phytase sequences (phyA) from 10 A. niger strains have been cloned and 9 sequences have been analyzed. The fragments contained 1344 bp encoding for 448 amino acids. The obtained phyA sequences showed 92.1-99.7 percent similarity and differed from each other by 3 to 106 nucleotides. The derived amino acid sequences indicated that phytases produced by the investigated A. niger strains might not be heat resistant. Phytases from A. niger strains CNTP 5150. CNTP 5149 , CNTP 5033, and CNTP 5091 might be active at acidic conditions and possess high specific activity with phytic acid. Based on sequence similarity, the studied enzymes might be classified under four phytases that have been reported for A. niger. The phyA sequences have been deposited at the GenBank with accession numbers HM369362. HM369363. HM369364, HM369365, HM369366, HM369368, and HM369369 corresponding to the A. niger strains CNTP 5150, CNTP 5148, CNTP 5149, CNTP 5032, CNTP 5033, CNTP 5090, and CNTP 5091, respectively.