An in vitro evaluation was made of the measurement of puffing behaviour using an orifice-plate cigarette holder. Four brands of cigarettes were compared ranging in tar yield from 4 to 16 mg, and each was studied with two puff profiles, the “early triangle” and the “square wave” pattern. Two flow rates were used for each profile giving maximum flows of 25.7 and 37.0 ml s-1(early triangle) and 12.0 and 36.7 (square wave), respectively, and four puff volumes, i.e. 15, 40, 65, and 90 ml for each profile/flow combination. Forty-eight cigarettes of each type were smoked (three for each profile/flow/volume combination). The studies emphasize the need for careful calibration of the alinear flow system and the value of reference volume standards. When calibrated with air, volume measurements on smoke at ambient temperature were overestimated by an average of 1.4 %. An average overestimation of 1.2 % was seen per 1°C rise in temperature. This rise in temperature occurred in the last few puffs, and was mainly influenced by the puff volume. There was much less difference when subdividing the data according to cigarette type, the early triangle or square wave profiles, or the two flow rates. With puff volumes of 15 ml there was virtually no temperature rise, and except at 90 ml the effect was only important in the last 20 % of the smoking period.