Title: Antibacterial properties of fluoride releasing glass Ionomer cements (GICs) and pit and fissure sealants on Streptococcus mutans. Background: Occlusal pit and fissures are the most susceptible sites for dental caries. The clinical effectiveness of GICs and fissure sealants in preventing caries is well-documented, but there is some concern about bacteria left beneath sealants. Objective: (1) Study the antibacterial activity of GICs and pit and fissure sealants. (2) Compare between these materials. Methodology: GICs (Fuji IX GP and Ketac molar) and pit and fissure sealants (Teethmate-F1 and Helioseal-F ). The strains was grown in the Brain Heart Infusion broth and was incubated anaerobically for 18 hours at 37°C and subcultured in MSB agar. Four wells measuring 5 mm diameter was prepared on each agar plate and the prepared materials was placed and further incubated anaerobically for 48 hours at 37°C. The zone of inhibition was measured. Results: All the materials tested showed antibacterial properties to varying levels except; among pit and fissure sealants it is Teethmate-F which showed more antibacterial property. Conclusion: Teethmate-F1 sealant showed more antibacterial property compared to Fuji IX and Ketac molar. Helioseal-F did not show any antibacterial property.