The COVID-19 pandemic is a global health problem that changed the course of the world. The pandemic began in the city of Wuhan, China in December 2019 and was finally declared a pandemic in March 2020 by the World Health Organization. This disease affects the respiratory system, causing various clinical signs and symptoms. The main pathophysiology of COVID-19 is inflammation, and it can affect a number of bodily systems and functions. One of the impacts of COVID-19 inflammation is the change of hemoglobin levels. This change in hemoglobin levels is an important issue that requires attention, because the level of an individuals hemoglobin represents their capability to carry and distribute blood. After reviewing previous research articles, it was found that COVID-19 patients have a tendency for hemoglobin decrease.