Introduction: Dengue fever is the most rapidly spreading arboviral infection with major public health consequences. Leucopenia, thrombocytopenia, hematocrit, elevated aminotransferases, low CRP and prolonged APTT, are useful predictive markers for early diagnosis of dengue infection. Objectives of the study: To study the clinical presentation and laboratory predictive markers of dengue fever, dengue with warning signs and severe dengue. Materials and Methods: Prospective hospital based study of 100 patients who were classified as dengue (DF), dengue fever with warning signs (DWS) and severe dengue (SD). Lab investigations included WBC count, Platelet count, Hematocrit, SGOT, SGPT, PT, APTT, INR, CRP. Clinical and laboratory parameters in the 3 groups of dengue fever were compared in the study. Results: Study group included 100 cases of which DF was 36%, DWS 52% and SD 12%. Commonest presenting symptom was fever, nausea and vomiting. Pain abdomen, hepatomegaly, splenomegaly, bleeding, jaundice were seen in DWS and SD group. Lab parameters: Mean WBC count was low to normal in all 3 groups. Platelet count was low in all groups. Hematocrit, SGOT/SGPT, PT /APTT/INR was progressively found to be increased in the 3 groups. Low CRP was found in all 3 groups. Conclusion: Reliable diagnosis of dengue fever in endemic areas can be done by clinical parameters like presence of nausea, vomiting, pain abdomen and hepatomegaly. Ascites, pleural effusion, shock, liver dysfunction and hemorrhage are the markers for severe dengue. Monitoring platelet count, hematocrit and WBC count is very useful for management of dengue cases.