The impact of using soy milk on various yoghurt properties was investigated.  Five treatments of yoghurt were made from soy, buffalo or cow milk or from their mixtures. Soy milk yoghurt possessed the lowest acidity, redox potential, total solids, fat, total nitrogen, ash, total volatile fatty acids, saturated fatty acids and total amino acids contents while the buffalo's milk yoghurt had the highest values for all the previous. Also, mixing of soymilk with buffalo or cow milk decreased these values in the resultant yoghurt. Conversely, Soymilk yoghurt had the highest level of unsaturated fatty acids and linoleic acid and α-linolenic acid. The count of Str. thermophillus was almost similar for fresh samples of soy, buffalo and cow milk yoghurt. Utilization of soy milk only or mixed with buffalo or cow milk in yoghurt manufacture clearly decreased the count of L. bulgaricus.  In conculosion mixing of buffalo or cow milk with soy milk increased the sensory evaluation scores of yoghurt produced.