The associations of long-term patterns of risk factors and the risk of incident atrial fibrillation (AF) are incompletely characterized. Among 4351 Framingham Study participants (mean age 50+/-11 years at baseline examination, 57% women) from the original and offspring cohorts, we defined longitudinal patterns, referred to as trajectories, of AF risk factors and a composite AF risk score using approximately 16 years of data. We used Cox proportional hazards models to examine the association of trajectories to 15-year risk of AF. During follow-up, 719 participants developed AF. Five distinct trajectory groups were identified for systolic blood pressure (BP): groups 1 and 2 (normotensive throughout), group 3 (prehypertensive), group 4 (hypertensive initially with decreasing BP), and group 5 (hypertensive and increasing BP). In multivariable-adjusted analyses, compared with group 1, groups 4 (hazard ratio 2.05; 95% confidence interval 1.24-3.37) and 5 (hazard ratio 1.95; 95% confidence interval 1.08-3.49) were associated with incident AF. Three trajectory groups were identified for antihypertensive treatment. Compared with the group with no treatment throughout, the other 2 groups were associated with increased risk of incident AF. Distinct trajectories for diastolic BP, smoking, diabetes mellitus, and the composite risk score were not associated with increased 15-year risk of AF. Longitudinal trajectories may distinguish how exposures related to AF contribute toward prospective AF risk. Distinct trajectory groups with persistently elevated systolic BP and longer antihypertensive treatment are associated with increased risk of incident AF.