ABSTRACT Background Left atrial (LA) enlargement is a reliable predictor of adverse cardiovascular events, and reduced atrial function is an independent risk factor for mortality in patients with amyloidosis. The objective of this study was to characterize the LA function in Mexican patients with a confirmed diagnosis of hereditary transthyretin amyloidosis (amyloid transthyretin [ATTR]) Methods All consecutive patients with diagnosis of hereditary ATTR who underwent a cardiac magnetic resonance study in the period from March 2016 to June 2017 were included in the study; the volumes and function of the left atrium were evaluated Results Patients were divided into two groups, one with and one without cardiac amyloidosis. Statistically significant differences were observed between both groups in terms of indexed maximal LA volume, 26 mL versus 35.9mL, p = 0.03; indexed minimal LA volume, 10.7 mL versus 13.6mL, p = 0.03; and indexed LA pre-contraction volume, 17 mL versus 22.4mL, p = 0.03. No statistically significant differences were observed between both groups when comparing neither different ejection volumes nor the different ejection fractions Conclusions Patients with hereditary ATTR with cardiac involvement have remodeling of the left atrium, with increased atrial volumes, without diminishing its function.