Evidence for Artificial Food colours (AFCs) association with allergies/intolerance/hypersensitivities and hyperactivity rea-ctions, remain controversial and inconsistent although AFCs are suspected to interact with immune system in yet to be discovered unknown mechanisms. In the present study, the effects of Allura Red, Carmoisine and Indigo Carmine on Reactive Oxygen Species (ROS) production by human Polymorph nuclear Leukocytes (PMNs) were investigated. Chemiluminescence (CL) method enhanced by luminol (5-amino 2,3-dihydro-1,4-phthalazine-dione) was employed to study the ROS generation by PMNs stimulated in vitro by Phorbol 12-myristate 13-acetate (PMA). Allura red, carmoisine and indigo carmine could produce an effectively marked and dose-dependent inhibition of ROS production by PMNs. The highest CL inhibition of 94 %, 95 %  and36 % was observed respectively for allura red and carmoisine and indigo carmine at their respective highest concentration. Future studies are required to understand complete implications of the present study results.