Background: Left ventricular hypertrophy (LVH) is an independent predictor of cardiovascular events, and evidence has been obtained that an increase of a normal left ventricular mass (LVM) or new-onset LVH over time augments cardiovascular outcomes. Methods: We addressed this issue in a sample of a general population at relatively low cardiovascular risk. We analyzed subjects with normal echocardiographic LVM enrolled in the PAMELA (Pressioni Arteriose Monitorate E Loro Associazioni) study to follow the increase of LVM over time and assess the prognostic impact of this change on the incidence of cardiovascular events (mean follow-up 18.5 years). Results: In 990 subjects with no LVH at baseline, there was a significant average increase of LVM (21.2%), LVMI _BSA (18.9%), and LVMI _HT (22.3%) more than 10 years later. About a quarter developed LVH. The LVMI _BSA change exhibited an association with the cardiovascular risk mortality during the following 18.5 years, and the association remained significant after adjustment for confounders (hazard ratio, 1.2 [1.0–1.5]). Similar findings were obtained for LVM in absolute values or indexed for height. The association was seen in both genders, but the link with the cardiovascular risk was statistically significant in males only. Conclusions: Thus, although over 10 years, the LVM increase does not reach a LVH status, it is associated with an augmented cardiovascular mortality risk. This suggests that it might be important to consider periodical LVM assessment, even when LVM is within the normal range, to timely detect its increase and cope with the need of cardiovascular risk restratification.