The studies on preparation of cow milk dahi by using probiotic cultures viz., Lactobacillus acidophilus (T1) and Lactobacillus delbrueckii sub sp. bulgaricus (T2) alone as well as in combination their of i.e. T1 ,T2 and T3. The control dahi (LF-40) contained on an average total solids 12.75, fat 4.08, protein 3.22 and acidity 0.75 % LA. The dahi prepared by using Lb. acidophilus (T1) and Lb. delbrueckii sub sp. bulgaricus (T2) alone, contained total solids 12.82 per cent and 12.80 per cent, fat 4.02 per cent and 0.91 per cent, respectively. Dahi (T3) made by using Lb. aciobphilus + Lb. delbrueckii subsp. bulgaricus contained on an average total solids 12.81, fat 4.08, protein 3.27and acidity 0.99 per cent lactic acidity. Dahi (T3) prepared by using combination of Lb. acidophilus and Lb. delbrueckii subsp. bulgaricus showed higher viable lactobacilli count (77 x 107c f.u./gm) than T2 (47 x 107c. f. u./gm) and T1 (30 x 107c f.u./gm) samples respectively. The sensory score for aroma of the dahi sample T3 showed maximum (7.90) and which was at par with control (T0) dahi and T1 dahi samples.