Malaria is one of the most widespread infections in the tropics, and also one of the most dangerous. There are four types of Plasmodium causing malaria of which Plasmodium vivax and falciparum are common in India. There is a huge burden of disease and it is responsible for increased mortality and morbidity. Due to paucity of research to quantify the severity and to predict the mortality risk of vivax malaria even though it affects multiple organ system during the course of the disease, this study was undertaken, to assess the severity of P. vivax malaria according to malaria severity score (MSS). The Aim of this study was to analyze the role of Malaria Severity Score (MSS) in predicting morbidity and mortality in patients affected by Plasmodium vivax infection.