Deoxyribonuclease (DNase) is an extracellular enzyme, produced by various microorganisms. In the present study, DNase producing microorganisms were isolated from different milk samples. They were screened for DNase production using DNase test agar with different indicators. Based on the morphological, biochemical and molecular characterization, the isolate VITSV4 was identified as Staphylococcus aureus. To enhance the yield of DNase, various parameters such as carbon, nitrogen, temperature, pH, incubation time and inoculum size were analysed. The incubation for 6 h expressed maximum DNase production at 25ºC. The optimum pH and inoculum size was found to be 5 and 1%, respectively. The protein content of crude and partially purified DNase was found to be 0.64 and 0.168 mg/mL and the maximum DNase activity was found to be 923.4 and 1198.8 U/mg, respectively. The molecular weight of the enzyme was determined as 30 kDa. The efficiency of DNase was tested by treating it with DNA isolated from different sources and the lysis was observed using agarose gel electrophoresis. © Shiraz University 2016.