This study evaluated the effect of a Probiotic mouthrinse containing nisin, a bacteriocin extracted from Lactococcus lactis on dental plaque and gingivitis in young adult population. A group of 32 subjects were randomly assigned into two groups of 16 each. The first group started using the control mouthrinse (placebo) for 2 weeks followed by a washout period of 4 weeks. This group then used the test mouthrinse (Probiotic) for a further duration of 2 weeks. The second group followed a similar protocol as the first except that this group started with the test mouthrinse (Probiotic). Plaque Index (PI) and Gingival Index (GI) were recorded at baseline and after 2 weeks for each group. All subjects were given full mouth prophylaxis after each measurements. The results of this study showed that rinsing with Probiotic mouthrinse resulted in a statistically significant reduction of plaque accumulation and gingivitis compared to rinsing with placebo. The results indicated that Probiotic mouthrinse containing nisin had the potential of inhibiting plaque accumulation and was effective in reducing gingivitis.