Abstract : To estimate IgE and histamine levels in patients with drug allergy and with past history of drug allergy. Compare these levels with that of normal individuals. Assess the association of demographic factors, nature of drugs and clinical presentation with IgE and histamine levels. 113 potential participants were totally interviewed. 66 selected based on selection criteria. 22 had current allergy (CA), 22 past history of allergy (PA) and 22 without any allergy (NA). Study was initiated after getting IHEC approval and informed consent from each participant. Estimation of serum IgE and histamine was done using ELISA kits. Demographic details, details of drugs and clinical presentation were recorded. Time interval between onset of allergy and estimation of IgE and histamine was recorded for patients with PA. Results were analyzed using ANOVA and student t test. p<0.05 was considered significant. IgE and histamine levels were significantly higher in CA compared to NA and PA subjects. Normal mean level IgE was 72.6 IU/ml and histamine 42.53 ng/ml. In PA levels were higher than that of NA but lower than CA. Males and civil workers had a higher level than females. Age related difference in the levels was not observed. NSAIDs induced allergy resulted in maximum elevation of IgE (538.74 IU/ml) and histamine (158.32 ng/ml) followed by antimicrobials (IgE 395.97 IU/ml) and histamine (133.42 ng/ml). Patients who developed maculopapular rashes had maximum level of IgE (627.87 IU/ml) and histamine (182.25 ng/ml). The time dependent decline in both the levels was observed in PA. Higher IgE level was associated with higher level of histamine in all the groups. CA, NSAIDs and maculopapular rashes resulted in maximum elevation of IgE and histamine. In PA, IgE level was higher than NA group. Whether estimation of IgE would indicate past allergy or the tendency to develop allergy has to be assessed by further studies.