Cigarette smoking cessation was examined for its impact on diastolic blood pressure, weight, and plasma lipids in 3,470 special intervention males in the Multiple Risk Factor Intervention Trial. Change in smoking status (quitters vs nonquitters) was not independently associated with change in diastolic blood pressure or the subsequent use of antihypertensive medication for smokers who were normotensive at entry. More quitters (35%) became hypertensive than nonquitters (27%, P less than 0.01), although the groups had similar baseline diastolic blood pressure levels. Weight gain subsequent to cessation probably contributed to this excess incidence of hypertension in quitters. Stepped-care antihypertensive therapy lowered diastolic blood pressure similarly for hypertensive quitters and nonquitters. Weight increases of 6 lb or more by the 72-month visit occurred in 47% of quitters vs 25% of nonquitters (P less than 0.01); quitters did not differ from nonquitters in their change in total kilocalories from baseline to the 72-month visit. Quitters who gained 6 lb or more tended to be less obese at baseline, be less physically active, and smoke more cigarettes per day than those who did not gain this amount. Finally, quitters relative to nonquitters experienced an adjusted increase of 2.4 mg/dl high-density lipoprotein cholesterol, but no difference in total or low-density lipoprotein cholesterol. The implications for intervention are discussed as they relate to the common, but not inevitable, increase in weight subsequent to cessation.