Dengue is a viral infection which has become a serious problem in recent years. It is a major cause of mortality and morbidity. The present study is a prospective, hospital-based, observational study done from August 2014 to October 2014. The objective of our study was to consider whether dengue infection can be suspected based on haematological and biochemical findings. The study included 100 patients positive for dengue infection. Complete hemogram, transaminases for liver injury, blood urea and serum creatinine levels for renal assessment were performed for these patients. The most common haematological findings were thrombocytopenia, leucopenia, an increase in the mixed cell fraction of the leucocytes and the presence of reactive lymphocytes. Biochemical parameters like the aminotranferases, blood urea and serum creatinine levels were significantly raised. Hence, a platelet count of <100,000 cells/μl, leucopenia of <4000cells/μl and aspartate aminotransferase levels of >82.2 U/L can be considered as predictors of dengue infection.