Calculus plays an important role in chronic inflammatory periodontal diseases. Currently, there is much interest in dentifrices that have the capacity to reduce the formation of calculus. Recent clinical studies have indicated that dentifrices containing soluble pyrophosphate and sodium fluoride can reduce the formation of supragingival calculus. The purpose of this study was to compare the effect on supragingival calculus of a dentifrice containing soluble pyrophosphate and 0.24% sodium fluoride to a placebo dentifrice. Thirty five subjects were stratified into balanced groups based on initial calculus scores. They then received an oral prophylaxis and were assigned to the use of either the placebo or soluble pyrophosphate/sodium fluoride dentifrice for the next 3 months. The results from the 3-month examinations indicated that the dentifrice containing the soluble pyrophosphate and sodium fluoride did not significantly reduce supragingival calculus as compared to the placebo dentifrice. However, both dentifrices reduced the calculus significantly.