Histamine as a primary heterocyclic amine has an important role in human physiology particularly in nervous system as a chemical mediator and neurotransmitter that was found in many foods such as cheese, milk, meat, fish, beer, wine and vegetables. Increasing of histamine concentration in foods is often related to low quality of raw materials, contamination, improper food processing or storage. Therefore, the amount of histamine content is used as a good indicator of hygienic quality in foods and the degree of freshness or spoilage of foods. Histamine can cause symptoms in sensitive consumers such as: redness of face, sweating, palpitations, headache, oral burning and bright red rashes. Cheese provides an ideal environment for the production of proteolytic releases of free amino acids and biogenic amines such as histamine. The aim of this study was to evaluate the amount of histamine in Koopeh cheese as one of the most popular types of traditional cheeses made from raw sheep milk or sometimes cow milk in West-Azerbaijan province, Iran. Experiments conducted by HPLC method on 70 samples of traditional Koopeh cheese revealed that the least amount of histamine was 2.43 ppm and the highest value was estimated at 1102.24 ppm. The average amount of histamine in cheese samples was 304.23 ± 150.89 ppm. Histamine production in cheese and other foods is based on the presence and growth of decarboxylase-positive microorganisms. Therefore, providing guidelines that reduce the population of these types of microorganisms will be effective on decreasing the amount of biogenic amines and histamine in particular