The aim of the present study was to determine the optimum pH, time, temperature, variety and concentration of the added fatty acid and the initial count of added Lactobacillus plantarum AB20-961 and Lactobacillus plantarum DSM2601 for high conjugated linoleic acid (CLA) production in ground beef. The highest CLA production with using safflower fatty acids by L. plantarum AB20-961 and L. plantarum DSM2601 was 7.91 and 38.31 mg CLA/g fat, respectively (P < 0.05). Optimum conditions for both strains were 37 degrees C fermentation temperature, 5% added fatty acid in free form and 8 log CFU/g initial count. Additionally, the optimum pH and fermentation time were 7.94 pH and 78.78 h for L. plantarum AB20-961 and 7.68 and 72.57 h for L. plantarum DSM2601. The results indicated that both L. plantarum strains with optimum conditions determined in the present study may be applied in order to enrich CLA content in ground beef and satisfy consumer demands for the fermented meat products with functional components.