Background: Overweight and obesity are in reported observational studies consistently associated with increased prevalence of asthma. Recently adipose tissue is considered as a source of inflammatory cytokines. Interleukin 4 (IL-4) mediates important pro-inflammatory functions in asthma, including induction of isotype rearrangement of IgE. Objective: The aim of the work was to assess IL4 in relation to Body Mass Index (BMI) in allergic asthmatic patients. Patients and Methods: 100 allergic asthmatic patients were enrolled in the study and classified according to BMI. All participants were subjected to routine laboratory investigations, serum IL4, skin prick test and pulmonary function tests. Results: IL-4 was significantly higher in overweight, obese and massive obesity patients [560 (440-720) pg/ml, 560 (410 -730) pg/ml, 830 (445 -1095 pg/ml respectively] in comparison to non-obese asthmatic patients [160 (80-280) pg/ml] (p<0.001). This difference in serum IL-4 level was strongly correlated to BMI (r=0.74) and body weight (r=0.69) (p<0.001). Simple linear regression analysis revealed a strong relation between serum IL4 and BMI (β = 0.705, p < 0.001). Conclusion: It could be concluded that there is a strong association between the inflammatory cytokine IL4 and BMI among obese allergic asthmatic patients, this may suggest a state of ongoing subclinical inflammatory state in the obese-asthma phenotype.