ABSTRACT. Marques A.P.L., Botteon R.C.C.M., Machado C.H., Medeiros B.P., Assis J.D., Barros J.P.N. & Araújo F.L. [Differential count of cells in the milk of cows with subclinical mastitis with the colorations of May-Grünwald Giemsa and Gram.] Contagem diferencial de células no leite de vacas com mastite subclínica com as colorações de May-Grünwald Giemsa e Gram. Revista Brasileira de Medicina Veterinária, 38(Supl.2):123-127, 2016. Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal Rural do Rio de Janeiro, Instituto de Veterinária, Departamento de Medicina e Cirurgia Veterinária, BR 465, Km 7, Seropédica, RJ 23897-970, Brasil. E-mail: email@example.com Somatic cell count (SCC) determines the amount of leucocytes and epithelial cells present in milk. It is used for monitoring the subclinical mastitis in the herd. Various tests can be used for SCC. For convenience and accuracy there is the electronic counting by flow cytometry. Microscopic slides count is the standard method for the determination of SCC in raw milk with the classic method described by Prescot and Breed (1910). This study aimed to evaluate the differential cell count in milk of cows with subclinical mastitis, by optical microscopy, in slides stained by May Grunwald-Giemsa and Gram. In both staining the cells showed morphological changes. However, the unidentifiable cell percentage did not exceed 10% enhancing the applicability of the differential cell counts, as used in leucocytes in hematologic smears. There were small variations in the counts with the two colorations. There was a predominance of neutrophils (˃60%), followed by lymphocytes (˃25%) consistent with the characterization of the samples as coming from rooms with subclinical mastitis. May Grunwald- -Giemsa stain showed similar results to Gram. The main differences between the colorations are based on the amplitude and intensity of staining, the Gram stain which stood out. In Gram staining of cytological entire background and other elements were evidenced. The Gram had the advantage of circular voids view corresponding to fat, enabling setting on the presence of neutrophils in milk for a long time, in some samples and identification of bacteria was easily accomplished. It is concluded that the viability staining Gram alternatively, and further is used as a complementary color, which would increase the representation of counts and the ability of observations of other elements in the sample.