The present study was conducted to evaluate the effect of natural substances as chitosan, thyme oil, lactic acid and acetic acid on microbial, chemical and sensorial quality of fresh meat slices during 18day of storage at 40C and periodically analysed for total mould counts, pH, surface colour (Hunter L*, a* and b* values), 2-thiobarbituric acid reactive substance and Total Volatile Nitrogen were measured on days 0, 3, 6, 9, 12, 15 and 18 day of storage. The obtained results showed that addition of tested antifungal and antioxidants, individually, affected colour, lipid stability and sensory attributes of the meat slices compared to control during storage. Chitosan (1.5, 1.0 and 0.5 % w/v) showed the most intense red colour than other tested antifungal and antioxidants (thyme essential oil, lactic acid and acetic acid) when compared to the control. Also, the results showed that the initial total count (day 0) value for the fresh meat slices was 1x106 CFU /g, then decrease gradually until 9 day not detected any colony by using chitosan 1.5%. While in treated samples with thyme oil 1.5% and lactic acid 1.5% ,the total mould values was 5.6x105 ±5.5x103 CFU /g at 15 days and 9.4x105 ±3.9x103 CFU /g at 12 days. Based on the results obtained in this study, the application of natural substances as chitosan, thyme oil, lactic acid and acetic acid were effective in preserving quality of fresh meat slices and is recommended in meat products.