BACKGROUND: One of the important parameters in assessing the definitive physical, mechanical, and biological characteristics of resin composites is the degree of conversion (DC), as composite qualities have been proven to improve with increasing the DC after photo-polymerization. Besides, fracture or secondary caries are the most common causes of composite resin failure. Accordingly, this reflects the need of formulating dental restorative materials possessing antibacterial activity. AIM: This study was designed to incorporate different concentrations of a new antibacterial agent (Octenidine dihydrochloride [OCT]) into an experimentally formulated flowable resin composite and evaluate its DC. MATERIALS AND METHODS: Four groups were tested in this study; group I was used as the control group, it’s a commercially available flowable composite “Herculite Ultra Flowable”. Group II was an experimental flowable composite with no antibacterial agent. During the preparation of the experimental flowable resin composite material, OCT antibacterial agent was added to the filler in special dark containers at a concentration of 1% wt. and 1.5% wt. respectively, in groups III and IV. The DC was measured and compared to the commercially available resin composite using the Fourier Transform Infrared spectroscopy method. RESULTS: Results of the current study showed that the mean values of DC ranged between (70.37 and 48.7), where Group1 showed the highest mean value, followed by Group 2 than Group 3, Group 4 specimens had the lowest mean value. The data showed that there is a statistically significant difference between all the tested groups. However, the DC was still within the accepted ranges for dental use. CONCLUSION: Based on the results obtained within the experimental conditions of this study it may be stated that the inclusion of the antibacterial OCT 1% and 1.5% wt., into the flowable resin composite showed satisfactory results for the DC as it met the ADA requirements for clinical use.