Covid-19 is a highly infectious disease caused by the new Coronavirus, which was identified in Wuhan in China and caused covid-19, 11,821 cases and 259 deaths were recorded in the first 30 days of infection, it is known that the disease causes clinical changes, so hematology is a type of test that analyzes information about the types and amounts of components in the blood as: Red blood cells; White blood cells; Platelets. The present study aimed to present the main hematological alterations found in patients hospitalized by Covid-19. The most prevalent mild symptoms include fever and cough, while in severe patient's respiratory failure occurs, so it is possible to observe in the blood test a significant decrease (10% -20%) of oxygen saturation. However, it was observed that there was a prevalence of changes related to leukocytes and platelets, however, lymphopenia was also present in reports made by authors.