Sheep milk is considered an important nutritional and health-promoting food source due to its high protein content and minerals. The current study aimed to ascertain the impact of probiotic bacteria (Bifidobacterium longum) on the physicochemical properties, bacterial evaluation and sensory assessment of stirred bio-yoghurt made from sheep milk. Stirred bio-yoghurt was prepared with various inoculation levels of Bifi. longum (3, 6, 9 and 12% for T1, T2, T3 and T4; respectively). According to the study's findings, the moisture content of all treatments steadily declined with increasing of storage periods at 4±1°C up to 15 days. The control samples had higher moisture than that of stirred bio-yoghurt made with various amounts of Bifi. longum. While the fresh samples had lower moisture that that of other treatments. The fat content of stirred bio-yoghurt as well as control samples found to decrease and significantly differences with increasing the storage periods at refrigerator temperature up to 15 days. In addition, the incorporation of Bifi. longum significantly raised protein and ash contents of stirred bio-yoghurt than that of control samples, and their contents were increase and significantly differences with increasing the storage periods at refrigerator temperature up to 15 days. There were astatically significant change in the syneresis of all moduli (treatment and control sample). Stirred bio-yoghurt treatments and the control samples had no coliform as well as mould and yeast levels in all treatments.