Introduction: Traditional buttermilk is a native beverage of iran, especially in villages, where it is consumed to a great extent during spring and summer seasons.Materials and Methods: Buttermilk is an aqueous phase obtained during the churning of yoghurt in Mashk for butter manufacturing. Buttermilk was traditionally made from sheeps milk in East - Azarbayjan (Meyaneh and Hashtrood) rural areas. The physical and chemical compositions of this product were investigated during three lactation periods (beginning, main point and the end). Therefore, 60 Iranian traditional buttermilk samples were collected from the Meyaneh and Hashtrood (30 sample from each zone) in order to determine physical and chemical properties of sour butter milk samples.Results: The results showed that pH, titratable acidity, total solid, ash, salt, crud protein, fat, lactose and density were in ranges of: 3.64 - 3.81, 0.91 - 1 (LA%), 3.51 - 5.47 %, 0.29 - 0.79 %, 0.16 - 0.27 %, 1.99 - 2.75 %, 0.16 - 0.45 %, 0.31 - 0.97 %, 1.0191 - 1.0264 g/cm3, respectively. The results indicated that there were significant differences between physical and chemical properties of samples were taken in different lactation periods (P≤0.05) but there were no significant differences in different zones (P≤0.05).Conclusion: It was concluded that the physical and chemical quality of Iranian traditional buttermilk comply with codex standard for yoghurt drink (doogh).