Malaria is one of the widely spread vector bond infectious disease responsible for grave health issues. Pakistan is one of the adversely hit country by malaria. We conducted this study to access whether there was only increase in no of malaria patients after flood in Sindh patients or clinical variance is also there. Objective: To assess the severity of Plasmodium vivax infection at a tertiary care hospital, after flood situation in Sindh. Methods: This cross-sectional study was conducted at LUMHS, Jamshoro from November 2022 to April 2023. After taking inform written consent, adult patients of age 13 to 60 years, irrespective of gender, with positive report of P. vivax malaria were included in the study. Data were recorded on predesigned proforma. Severity of malaria was determined according to the classification criteria. Data were analyzed with the help of SPSS version 23. Results: Out of total 170 patients, 52.4% female, mean age was 26.6 year. 50.6% patients of Plasmodium vivax found to suffer from severe malaria. Severe anemia, ALOC and jaundice were present in 28.2%, 21.2% and 11.2% of patients respectively. Conclusions: Enormous number of severe malaria cases due to of P. vivax was detected after floods in Sindh. Young age people were affected more, irrespective of gender. Severe anemia was the most common complication of malaria. Thrombocytopenia found frequently in patients infected with P. vivax.