Abstract Background Echocardiographic reference values for interventricular septal (IVS) thickness (upper reference limit [URL] 11.2 mm in women vs. 12.4 mm in men), and posterior wall (PW) thickness (URL 11.5 mm vs. 12.3 mm, respectively) exist. According to a European Society of Cardiology position statement, cardiac amyloidosis (CA) should be suspected when left ventricular (LV) wall thickness is ≥12 mm and at least one red flag is present. Given the normal difference between men and women, a same cut–off might cause a diagnostic delay in women. Methods Consecutive patients diagnosed with amyloid transthyretin (ATTR)–CA at 3 centers were evaluated. Results The cohort included 302 patients (Pisa, n=215; Brescia, n=58; Trieste, n=29). Women (n=49, 16%) were older than men (median age 83 years [interquartile range 80–85] vs. 80 years [76–84], p=0.009), but their survival free from all–cause death (p=0.380) or heart failure (HF) hospitalization (p=0.381) did not differ significantly. N–terminal pro–B–type natriuretic peptide values (p=0.897), the proportion of patients with variant ATTR (p=0.369), the prevalence of hypertension (p=0.659), diabetes (p=0.629), or New York Heart Association class III–IV (p=0.613) were not different. LV ejection fraction was 53% (43–60%) in women vs. 50% (43–65%) in men (p=0.066), and tricuspid annular plane systolic excursion was 16 mm (13–20) in women vs. 16 mm (14–19) in men (p=0.674). Even relative wall thickness (RWT) did not differ significantly (0.61 [0.49–0.98] in women vs. 0.69 [0.57–0.87] in men; p=0.448). Conversely, women had lower IVS (15 mm [14–18] vs. 17 mm [15–20]) and PW thickness (13 mm [12–16] vs. 15 mm [13–17]). These differences disappeared when IVS and PW thicknesses were indexed for height (as m), height2,7, or body surface area: IVS, p=0.150, 0.212, 0.325, respectively; PW, p=0.309, 0.107, 0.743, respectively. Conclusions At the time of diagnosis, women with ATTR–CA are older, but their biventricular function, the pattern of LV remodeling, and final outcome did not differ significantly from men, suggesting a similar disease stage. Even indexed IVS or PW thicknesses are similar, while non–indexed measures may point to a less advanced disease and then be misleading. Indexed measures or sex–specific cut–offs (e.g., 11 mm in women vs. 12 mm in men) to suspect CA might be considered.