Dengue-COVID-19 overlap is mixture of both diseases sharing few similarities in pulmonary and extra pulmonary involvement.Methods: Prospective, observational study, included 300 COVID-19 cases with dengue NS1 or dengue IgM positive, with lung involvement documented and categorized on HRCT thorax at entry point. All cases were subjected to dengue IgG antibody titers and dengue IgM/IgG antibody titer analysis after 12 weeks of discharge form hospital.Results: Hematological evaluation, white blood cell count & platelet count were having significant association with dengue-COVID-19 overlap (p<0.0076) & (p<0.00001), respectively. Clinical parameters as hypoxia have significant association with dengue-COVID-19 overlap (p<0.00001). Inflammatory markers as IL-6, CRP, and LDH has significant association in dengue-COVID-19 overlap (p<0.00001), respectively. Dengue-COVID-19 overlap was documented in 16.33% (49/300) cases. CT severity has documented significant correlation with dengue-COVID-19 overlap cases (p<0.00001). In study of 49 cases of 'dengue-COVID-19', post-COVID-19 lung fibrosis (p<0.004), and serological assessment in dengue IgM/IgG and COVID-19 antibody titers has significant association (p<0.00001). Conclusion:'Dengue-COVID-19' is disease of concern in ongoing pandemic in critical care setting, and timely workup is crucial step in preventing delay in diagnosis and final adverse outcomes.