Nowadays, modified atmosphere packaging (MAP) is one of the most important method to extend the shelf life of fresh meat without loss of its keeping quality. On the other hand, the use of lactic acid spray (mostly 1%) has been considered to reduce microbial load on car case surface in the abattoirs of many countries, thus it is possible to use this solution for improvement of storage life of packaged meat. In order to compare the effects of 4 packaging methods (normal packaging and 3 kinds of MAP i.e, N2%80 + Co2%20, N2%60 + Co2%40, N2%50 + Co2%50) and their combination effects with %1 lactic acid on the shelf life of mutton, samples were treated by lactic and ofther packaging the ire samples together with those without any treatment weretaken kent samples without treatment and in chilling room at 30 C, they were taken out at 4th day and next days (with 3 days intervals) and examined by chemical, microbial and organoleptic tests. The final results were as follow: The shelf lives of meat in normal packaging, N2 %80 + Co%20, N2 %50 + Co2%50 and N2 O/O + Co2%40 were 4,10,10 and 13 days respectively. Additionally, because of significant reduction of chemical and microbial parameters in normal packaged beef by %l lactic acid spray, this treatment is recommended to improve keeping quality of normal packaged meat.