Milk adulteration and its hygienic quality has become a global concern particularly in developing and underdeveloped countries. So, the awareness of consumers about the common adulterations and the quality level of milk and dairy products are important. The present study was carried out to determine the common chemical adulterants added to raw cow milk by the suppliers from rural areas in the northwest of Iran. Furthermore, the hygienic quality of samples was investigated. A total of 100 samples of raw cow milk were randomly collected from different local markets of dairy products in the northwest of Iran. The results showed that formalin and sodium bicarbonate were present in 8 and 10% of the raw milk samples respectively. However, the adulteration with starch, sugar or skim milk powder, detergents, pulverized soap, chromate and dichromate, hydrogen peroxide were not determined in any of the samples. The mean pH values of collected samples were 6.46±0.11. The methylene blue reduction test also showed that only 44% of raw milk samples had proper hygienic quality. The results of Alcohol test and Clot-on-boiling test were positive in 20 and 43% of samples respectively. The total bacterial count of raw cow milk was in the range of 5.65 to 6.19 log cfu/ml. The results of present study showed that raw cow milk samples did not meet recommended standards, had poor hygienic quality and adulterated with formalin and bicarbonates which are harmful to the health of consumers.