BACKGROUND: Dengue is estimated to pose a risk to half of the world's population and represents a significant global economic burden. In Malaysia, dengue is a major cause of morbidity and infectious disease mortality, with an annual upward trend in nationally reported cases. The identification of dengue patients upon presentation, specifically, the diagnosis, classification and management of cases, can be challenging due to the wide spectrum of disease manifestation. Current case definitions and classifications of dengue can be difficult to apply in practice. Often, clinicians in low and middle income countries must rely on a clinical diagnosis due to the absence or delay of obtaining reliable laboratory test results. Although many studies have assessed the application of the 1997 and 2009 WHO dengue case management guidelines to manage dengue, there is limited qualitative research exploring how clinicians identify and triage dengue cases during an outbreak in a hospital setting. METHODS AND MATERIALS: An ethnographic study conducted at an urban public hospital in Malaysia explored day-to-day dengue case management, with a focus on the triaging and diagnosis of dengue on the Emergency and Infectious Disease wards. The study employed ethnographic, qualitative methods, specifically direct observation, interviews and focus group discussions with doctors and nurses in two hospital departments. Fieldnotes and verbatim interview and focus group discussion transcripts were analysed using a modified thematic content analysis approach. RESULTS: Preliminary findings identified the challenges of identifying dengue in patients with atypical and typical presentations, with implications for patient morbidity and mortality. The diagnosis of dengue was complex; reliant on a detailed patient history, enhanced clinical assessment and where possible, laboratory diagnostic tests ranging in reliability. The uncertainty of dengue diagnostic tests, delays in receiving the results and the non-specific nature of dengue illness constituted challenges that clinicians faced when triaging, diagnosing and managing patients. CONCLUSION: This study provides in-depth insights into how dengue cases are triaged and diagnosed at a hospital during an outbreak and the limitations of existing dengue case definitions. The findings from this research may be useful to other tertiary care settings in dengue endemic countries.