The antibiotic residues and pathogenic resistance against the drug are very common in poultry due to usage of antibiotics in their feed. It is the need of the time to use natural feed additives as effective alternatives instead of synthetic antibiotic. The aim of this study was to investigate the immune response of Nigella sativa and Curcuma longa in broilers under biological stress against Pasteurella multocida. The total 100, one-day old chicks were divided into 5 groups. The Groups 1 and 2 were served as control negative and control positive. Both control groups were receiving simple diet without any natural feed additives but infection was given in Group 2 at day 28 with the dose of 5.14×107 CFU by IV. Groups 3A & 3B were offered 2% seed powder of Nigella sativa, Groups 4A & 4B were offered Curcuma longa 1% in powdered form and Group 5A & 5B were offered both Curcuma longa 1% & Nigella sativa 2% in feed from day 1 and groups 3B, 4B and 5B were challenged with Pasteurella multocida. The Haemagglutination inhibition titter against Newcastle Disease Virus (NDV), feed conversion ratio, mortality, gross and histopathology were studied. The results of this study revealed that haemagglutination inhibition titers against NDV were highly significant (P< 0.05) in treated groups, highest titers (3A 6.8, 3B 6.4 and 5A 7.2) were obtained from treated Group. The feed conversion ratio (FCR) of Nigella sativa + Curcuma longa treated Groups (5A 1.57 and 3A 1.76) were higher as compared to other non-treated groups. The gross and histopathological changes were much severe in control positive, but less changes were seen in treated groups. Therefore, we recommend that natural feed additives; black cumin (Nigella sativa) and turmeric (Curcuma longa) act as immune enhancer in broilers against Pasteurella multocida.