Light-to-moderate regular alcohol consumption has been associated with reduced mortality, heart failure, and sudden death, with a well described "U-shaped" relationship. We sought to determine whether markers of diffuse ventricular fibrosis as assessed by cardiac magnetic resonance imaging (CMR) T mapping differ between nondrinkers and regular drinkers. We prospectively recruited 165 participants to undergo 3T CMR ventricular T1 mapping which included 120 regular light-to-moderate drinkers (7 to 28 standard drinks per week for >12 months) and 45 age and gender-matched nondrinking controls (1 standard drink ∼12 g alcohol). Diffuse ventricular fibrosis was assessed using ShMOLLI T1 mapping sequences performed in mid-short axis. Native T1, postcontrast T1 times and extracellular volume were compared in the left ventricle between regular drinkers and lifelong nondrinkers. In total 165 participants (mean age 59 ± 12 years, 70% male, 36% hypertension, mean LVEF 58 ± 11%) underwent CMR. Moderate alcohol intake (mean alcohol intake 16 ± 6 SDs/week) was associated with lower markers of diffuse ventricular fibrosis: native T1 time 1140 ± 47 vs 1173 ± 39 ms, p < 0.001; postcontrast T1 time 470 ± 47 vs 445 ± 43 ms, p = 0.01; extracellular volume 25.0 ± 2.7% vs 27.0 ± 2.8%, p = 0.003 despite similar LV size (p = 0.55) and mass compared with nondrinkers (p = 0.78). Quantity of alcohol intake and beverage type did not predict lower native T1 times. In conclusion, light-to-moderate or "social" alcohol consumption is associated with T1 changes on CMR suggestive of a reduction in diffuse ventricular fibrosis. These preliminary findings may provide some insights into the association between modest alcohol intake and reduction in sudden death and heart failure.1