Background: In 2015, Delhi city experienced the worst outbreak of dengue infection since 1996 and our laboratory received a very high number of cases for IgM ELISA testing following clinicians’ referrals. The present study intends to correlate IgM antibody response with duration of fever, platelets counts and ‘with age and gender distribution’ of such cases attending OPDs and subsequently admitted to the medicine and pediatric wards in our tertiary care hospital, New Delhi, albeit, with some useful conclusions and suggestions.Methods: A hospital based observational study was conducted enrolling a total of 500 cases, clinically suspected of DF/DHF/DSS that either reported directly or were referred to Safdarjung Hospital from region in and around Delhi and NCR and subsequently admitted to Emergency Medicine and Paediatrics wards. A total of 500 cases and 50 controls were tested for IgM antibody by ‘IgM antibody capture ELISA (MAC ELISA).Results: Of total 500 serum samples tested, 169 i.e. 33.8% were found to be sero positive. Seropositivity was more among the males 99/169 (58.57%) than the females 70/169 (41.43%). The highest numbers of cases were seen in the age group 41-60 years (46.15%). Amongst seropositive cases, 146 (86.39%) cases had fever of >5 days duration while remaining 23 (13.60%) presented with fever of <5 days. Low platelet count between 20,000-1L cells/mm3 was a feature in all the seropositive cases and statistically it was found significant (p-value 0.001).Conclusions: Detection of IgM specific antibodies by MAC ELISA in cases with high index of clinical suspicion continues to be an effective tool providing a supportive criterion to clinical diagnosis, especially during outbreak periods.