This study was conducted to prolong the period of validity of diluted yoghurt by adding 0.5g, 0.75g and 1g of garlic per 1liter milk during the storage period of 50 days at 4 ± 1C °and 10 ± 1C°. Some of microbial, chemical and sensory parameters of yoghurt were identified on weekly bases from 1 till 49 days of the storage period. Results indicated that the vital force as a microbial parameter was lasted for 7 days in the control samples while it was lasted with for 35, 42, and 49 days for the samples containing 0.5, 0.75 and 1g of garlic, respectively when samples stored at 4±1C°. There were no significant differences in the vital force between control and treated samples when they stored at 10±1C°. Sensory properties of diluted yoghurt were more favorable in samples containing 0.5g of garlic (absence of taste and smell of garlic) in comparison with control samples or with samples containing higher proportions of garlic. Results also indicated that adding garlic did not affect either the pH of diluted yoghurt or the values of its sensory properties during storage periods and increased the safety of consumption up to 49 days of storage while this safety did not extend behind 7 days in control samples. It was concludes that adding garlic by 0.5 g/ liter of diluted yoghurt can increase its shelf life for 49 days.