When udder becomes inflamed during lactation, significant increase of somatic cells count in milk occurs. That is why an express-test based on surfactant’s effects was created. For this purpose 3 groups of samples were formed according to the somatic cell count in cm 3: group 1 - over 4.0*10^5 per cm3 (60 samples); group 2 - up to 4.0*10^5 in cm3 (100 samples); group 3 (control) - 3.0*10^5 in cm3 (30 samples). Experiments were conducted in the spring-summer and autumn-winter periods. Total amount of examined samples is 190. Somatic cell count in the samples was counted by viscometric method with the use of “Somatos-B.” We use the milk of animals 10–15 days after calving. Milk was mixed 1:1 with reagent, then after 3–4 tube shaking a height of foam column was determined. In the presence of somatic cells the foam forming is depressed. There was a positive reaction with column’s height from 3 to 10 (foaming) and negative reaction is considered to be from 0 to 3 (no foaming). There was a California mastitis test (CMT) as a control which is highly usable as an express-test in Leningrad region of Russia. The comparison of the results of two test show: on group 1 according to CMT 40 samples were positive, and foaming test determined 60 cases of somatic cells count increasing. On 2 group according to CMT 10 samples were positive and foaming test determined 60 cases of somatic cells count increasing. On 3 group according to CMT 1 sample was positive and foaming test not determined any somatic cells count increasing. This express method is not requires a big amount of time – it takes 8–10 seconds to mix a reagent and milk and evaluate results. So this method allows us to increase the mastitis diagnostic accuracy.