A study was made of the effect of the puff profile on yield and composition of the mainstream smoke of cigarettes smoked on a RM 20/68 smoking machine producing three different puff profiles (square-shaped profile, early peak and late peak profiles). The smoke was precipitated in an electrostatic trap. Crude condensate, dry condensate, smoke nicotine, phenols, puff number, and draw resistance were determined. Significant differences were found between the dry condensate yields of two puff profiles and between the nicotine and phenol yields of all the three puff profiles.