Purpose: The aim of the present study was to compare the effect of systemically administered lycopene (LycoRed™) as a monotherapy and as an adjunct to scaling and root planing in gingivitis patients. Materials and Methods: Twenty systemically healthy patients showing clinical signs of gingivitis were involved in a randomised, double-blind, parallel, split-mouth study. The subjects were randomly distributed between the two treatment groups: experimental group (n = 10), 8 mg lycopene/day for 2 weeks; and controls (n = 10), placebo for 2 weeks. Quadrant allocation within each group was randomised with two quadrants treated with oral prophylaxis (OP) and two quadrants not receiving any form of treatment (non-OP). Bleeding index (SBI) and non-invasive measures of plaque (PI) and gingivitis (GI) were assessed at baseline, 1 and 2 weeks. Salivary uric acid levels were also measured. Results: All the treatment groups demonstrated statistically significant reductions in the GI, SBI and PI. Treatment with OPlycopene resulted in a statistically significant decrease in GI when compared with OP-placebo (p 0.05) and non-OP-placebo (p 0.01). Treatment with non-OP-lycopene resulted in a statistically significant decrease in GI when compared with non-OPplacebo (p 0.01). The OP-lycopene group showed a statistically significant reduction in SBI values when compared with the non-OP-lycopene group (p 0.05) and the non-OP-placebo group (p 0.001). There was a strong negative correlation between the salivary uric acid levels and the percentage reduction in GI at 1 and 2 weeks in the OP-lycopene group (r = -0.852 and -0.802 respectively) and in the non-OP-lycopene group (r = -0.640 and -0.580 respectively). Conclusions: The results presented in this study suggest that lycopene shows great promise as a treatment modality in gingivitis. The possibility of obtaining an additive effect by combining routine oral prophylaxis with lycopene is also an exciting possibility, which deserves further study. Palabras clave: antioxidant therapy, gingivitis, gingivitis therapy, lycopene