OBJECTIVE: The early identification of patients at risk of severe dengue infection is critical to guide clinical management. There is currently no validated laboratory test, which can predict severe complications of dengue infection. The Atypical lymphocyte count (ALC) and Neutrophil-Lymphocyte Count Ratio (NLCR) is a research parameter generated at no extra cost when an automated Full Blood Count (FBC) is performed. The purpose of this study was to assess ALC and NLCR for predictor of the severity of dengue infection.                  METHOD: We prospectively collected data on patients admitted to Dr.Moewardi General Hospital with dengue infection between February - April 2019. Dengue infection was diagnosed based on WHO Criteria 2009. ALC, NLCR, and clinical data were extracted from medical records.                                                                                                                            RESULT: Fifty patients were enrolled. Patients with clinical manifestations of severe dengue have a significantly higher ALC compared to dengue without warning signs with cut of point >2371.5 has sensitivity 80.0% and spesificity 84.4%. Patients with severe dengue has higher NLCR compared to dengue without warning signs with cut-off point NLCR >3.52 with sensitivity 80.0% and sensitivity 82.2%.                                                                                 CONCLUSION: Predictor of severe dengue infection have a significantly higher ALC with sensitivity 80.0% and spesificity 84.4% and higher NLCR compared to non severe dengue with sensitivity 80.0% and sensitivity 82.2%.