The aim of the study was to examine whether triclosan has an effect on developing gingival inflammation. 10 volunteers, with clinically healthy gingivae were enrolled. The study was performed as a 2-week, double-blind, cross-over, experimental gingivitis trial. Between each plaque accumulation period, there was a wash-out phase of 4 weeks. A baseline examination was performed which included assessment of plaque and gingivitis. The volunteers were asked to refrain from mechanical oral hygiene measures for 2 weeks. During this period, they rinsed 2x daily with one of the randomly assigned mouthrinse preparations. Solution A (period A): 0.06% triclosan+ 2%tween 80. Solution B (period B): 0.06% triclosan+ 0.25% sodium lauryl sulphate. Re-examinations were performed on days 4, 7, 11 and 14. The mean plaque score increased during period A to 2.2 (day 4), 2.8 (day 7), 3.1 (day 11) and 3.1 (day 14). The corresponding scores for period B were significantly lower; 1.2 (day 4), 1.8 (day 7), 2.0 (day 11) and 2.2 (day 14). The mean gingivitis scores at baseline were 0.17 (periods A and B). The mean gingivitis scores increased to 0.45 (day 4), 0.69 (day 7), 0.83 (day 11) and 0.96 (day 14) when the subjects rinsed with solution A and 0.42 (day 4), 0.64 (day 7), 0.78 (day 11) and 0.92 (day 14) in period B. There were no statistically significant differences between periods A and B with respect to gingivitis. Thus, although significantly more plaque formed during period A than period B, no differences could be found between the gingivitis scores in the 2 periods.