Mastitis is an inflammatory immune reaction of the mammary gland, which is characterized by an influx of somatic cells into the milk. Bovine mastitis places a heavy economic burden on dairy sectors. In mastitis milk, microbial load and concentration of blood serum albumin, immunoglobulins,lactoferrin, sodium and chloride increase, whereas the content of lactose, casein, fat, different kinds of vitamins and minerals such as vitamin B1, B2, C, calcium, phosphorus, potassium and zinc decrease, and also intramammary infections cause an elevation of enzymatic activity of milk by increasing the concentration of different kinds of proteases such as plasmin, different types of cathepsin, elastase, and enzymes like lipase, b-glucuronidase, and catalase. These enzymes cannot be inactivated by thermal processing, thus they can affect the quality and shelf life of dairy products like yoghurt, milk powder, liquid pasteurized and UHT milk, and also enzymatic hydrolysis of casein result in decline in cheese yield. It seems that mastitis deteriorates the attributes of dairy products; therefore the main purpose of the present study is to review the importance of somatic cell count levels throughout the whole milk supply chain. It can be concluded that effective herd mastitis prevention and control programs on farm level in order to improve the quality of raw milk and dairy products, is essential.