Influence of various conditions on crossflow microfiltration of disrupted Arthrobacter luteus cells has been analyzed. Evaluation of permeate flux and transmission of macromolecules through the membrane demonstrates that the 750 kDa MWCO polysulfone membrane is the most efficient. Ionic strength, cell concentration, and pH have the highest influence on the yield of AluI restriction endonuclease. Meanwhile, the flocculation and decreased pH have the largest effect on performance of crossflow microfiltration. Flocculation with polyethyleneimine (PEI) have increased the permeate flux to 45.7 Lh(-1)m(-2) and pH5.5 decreased the flux to 22.2 Lh(-1)m(-2). In conclusion, optimal conditions for crossflow microfiltration of A. luteus cells lysate have been identified.