Background: Dengue Fever is a self-limiting arboviral infection characterised by fever, headache, myalgia, rash, nausea, and vomiting. A main feature of severe dengue is capillary leakage of which acalculous cholecystitis is considered as an atypical presentation. Aims and Objectives: To study the prevalence of Acute Acalculous cholecystitis and its correlation with the severity of dengue fever. Materials and Method: Serologically confirmed 540 cases of dengue fever who were hospitalized were included in the study. Detailed clinical examination, various laboratory parameters viz. Complete blood count, coagulation profile, biochemical investigations (renal function test and hepatic function test), and ultrasound of the abdomen were done. Patients were followed up from admission to discharge or death. Data was analysed with the statistical package SPSS 1.0.0.1406. The Chi-square test was used for the analysis of variables. P-value of <0.05 was considered significant. Observations: This study included 540 patients with a male and female ratio of 1.07:1. Patients presented with acute abdomen with or without complications like Shock, DHF, Hepatic or Renal dysfunction, and/or multiorgan dysfunction. Acalculous cholecystitis was observed in 39.6 % of cases (n=214). Conclusion: Acute cholecystitis occurred in a significant proportion of patients with dengue fever and this complication should be considered alarming in endemic areas.