Marek’s disease is a viral lymphoproliferative disease of poultry characterized by the creation of lymphoma in muscle, skin, eye or internal organs. Virus maturing into infective forms in follicular epithelium from where enters in the external environment where long time remains infectious. Poultry are infected by dust and remains the holder of the virus throughout their lives. The virus is transmitted vertically. The disease can occur in three forms: nervous, visceral and skin. Affected poultry may have any shape or combination of these. The aim of this study was to determine the cause of the disorder the health status in the flock of holland white crested chickens. Flock had 25 chickens whose ages ranged from 4-16 weeks. Observation, we noticed that the chickens are cachectic, showing signs of sporadic diarrhea and died 3 hens and 2 roosters. Pathoanatomical examination is ascertained changes in certain internal organs. The liver was enlarged with lymphoid proliferate on the surface and in the parenchyma, spleen increased several times and marbled, glandular stomach (proventriculus) dilated with petechial hemorrhages on mucose. Changed organs was examination histopathological. In the liver were observed multifocal lymphoid infiltration with subsequent atrophy of the parenchyma, in addition to spleen lymphoid proliferation heterophyllus and histiocytic infiltrates, in proventriculus lymphoblastic infiltration with congestion of capillaries and small haemorrhages. In samples pathologically altered organs PCR method proved the genome of Marek’s disease virus serotype 1 . Based on these results we concluded that the livestock were sick from Marek’s disease, which is expressed in visceral form.