Introduction: Thymoquinone is one of the phytochemicals used as chemopreventive agents for oral cancer control. TQ loaded on nanoparticles had shown higher anti-proliferative and anti-inflammatory effects than free TQ. Natural products that can inhibit Cyclooxygenase-2 (COX-2) would be a better choice in the prevention of tumor development with fewer side effects than pharmaceutical agents. Objective: To study the expression of Cox-2 in HBP/DMBA carcinogenesis model following combined topical application of TQ loaded on gold nanoparticles on alternative days. Material and Methods: This research was carried out on archival paraffin blocks of a previous thesis. The paraffin blocks represented hamster buccal pouches (HBPs) from 85 male Syrian golden hamsters were divided into 2 groups. The control groups included: I: negative control group, scarified at day zero then after 7 and 14 weeks, and II: positive control, treated with 7, 12-Dimethylbenz [a]-anthracene (DMBA) for 7 and 14 weeks. The experimental groups included: (III, IV and V) which were treated with the chemopreventive agents for 2 weeks then combined DMBA and the chemopreventive agents on alternative days for 7 and 14 weeks. Sections of 5µm were cut and processed for H&E and IHC stains for light microscopic study. Results: Negative and self-control groups showed negative COX-2 immunoreactivity. Group II showed intense Cox-2 immunoreactivity at both 7 and 14 weeks. Groups; III and IV showed moderate and intense Cox-2 immunoreactivity at 7 and 14 weeks, respectively. Group V showed mild and moderate Cox-2 staining reaction at 7 and 14 weeks, respectively. Conclusion: Topical application of G-NPs-TQ (0.001) for 7 and 14 weeks was able to reduce Cox-2 expression and in turn retard the carcinogenesis process due to its anti-inflammatory effect.