Smoking patterns are changing to accommodate new environmental smoking restrictions. The current study explored the effects of prior smoking amounts on the behavioral, physiological, and subjective effects of smoking a single cigarette. Ten smokers (six females, four males) each participated in four laboratory sessions of 6 h duration. During each session, they smoked 0, 2, 5, or 11 cigarettes which were evenly spaced throughout the 6-h period at intervals ranging from 30 min (11 cigarettes) to 120 min (2 cigarettes), with condition order determined by a Latin square. At the end of each session, all smoked a final cigarette. Response to the last cigarette of the 6-h session was influenced by pretreatment smoking amounts. Number of puffs drawn from the cigarette (15.0, 14.1, 13.3, and 10.1) was inversely related to prior smoking density, as was heart rate increase (5.8, 4.0, 2.4, and 1.3 bpm). Three physical symptoms of smoking, dizzy, lightheaded and tingling, were significantly greater when preceded by 6 h of no smoking than when preceded by smoking at 30-min intervals. However, these symptoms were rated as mild (19-27 on a 100-point scale) even when no cigarettes had been smoked. These results suggest some dissipation of acute tolerance after 6 h of smoking abstinence. Liking and satisfaction ratings were inversely related to the pretreatment density of smoking. Liking scores for the last cigarette were 85, 71, 68 and 48 (on a 100-point analog scale) when 0, 2, 5 and 11 cigarettes had been smoked. Overall, the study showed that physiological and subjective effects of smoking are modulated by recent histories of smoking.(ABSTRACT TRUNCATED AT 250 WORDS)