Background. The incidence of new-onset atrial fibrillation (AF) is increased by uncontrolled hypertension, and antihypertensive treatment reduces new-onset AF. However, it is unclear whether alcohol intake and smoking influence the risk of new-onset AF during antihypertensive treatment. Methods. In the Losartan Intervention For Endpoint reduction in Hypertension (LIFE) study, a double-blinded, randomized, parallel-group study, 9193 hypertensive patients with electrocardiogram (ECG)-documented left ventricular hypertrophy (LVH), randomized to once-daily losartan- or atenolol-based antihypertensive therapy were followed for a mean of 4.8 years. At baseline, 8831 patients (54% women, mean age 67 years, mean blood pressure 174/98 mmHg after placebo run-in) had neither a history of AF nor AF on ECG, and they were thus at risk of developing this condition during the study. Results. New-onset AF occurred in 353 (4%) patients. Univariate Cox analyses showed that intake of alcohol > 10 units/week compared with less or no alcohol intake predicted new-onset AF (Hazard ratio, HR = 1.60 [95% CI 1.022.51], p = 0.043). Multivariate Cox regression analysis showed that intake of alcohol > 10 units/week predicted new-onset AF (p = 0.010) independently of most other univariate predictors, except when also baseline serum cholesterol, serum potassium and urinary albumin/creatinine ratio were included in the model (HR = 1.60 [95% CI 0.942.72], p = 0.081). Impact of smoking was not significant in Cox univariate or multivariate analyses, and there were no significant interactions between high alcohol intake and either smoking or gender on the risk of getting AF. Conclusions. Up to 10 drinks of alcohol per week appears to be safe with respect to the risk for AF in hypertensive patients with LVH. Our data suggest that alcohol intake above this level may be marginally deleterious, while no effect of smoking on risk of AF was detected in hypertensive patients with LVH.