The purpose of the present study was to assess the effect of three different formulations of chlorhexidine gel in the concentrations of 0.2%, 1% and 2% for the control of plaque accumulation and gingivitis. This was a double-blind, longitudinal, non-crossover study in 48 children between 7 to 11 years of age. Subjects were randomly assigned to 4 different groups: G 1 (placebo), G 2 (0.2% chlorhexidine gel), G 3 (1% chlorhexidine gel) and G 4 (2% chlorhexidine gel). The chlorhexidine gel was administered once a week during 4 weeks. The clinical evaluations were made after 1 week, 1, 3 and 6 months of the last application of the chlorhexidine gel. Mean plaque and gingival scores were reduced over the fourweek trial period for experimental and control groups. There was no significant difference (p<0.05) between the groups treated with chlorhexidine gel when compared with the placebo group in the reduction of plaque and gingival scores. The results indicated that different formulations of chlorhexidine gel did not produce an effective inhibitor of plaque growth. Within the limitations of the present study design, further studies are required to clarify the role of chlorhexidine to prevent caries and periodontal disease.