Aims Transthyretin amyloid cardiomyopathy (ATTR‐CM) is predominantly diagnosed in men. The few available studies suggest affected women have a more favourable cardiac phenotype. We aimed to characterize sex differences among consecutive patients with non‐hereditary and two prevalent forms of hereditary (h)ATTR‐CM diagnosed over a 20‐year period. Methods and results Analysis of deep phenotyping at presentation, changes on serial echocardiography and overall prognosis were evaluated. In total, 1732 consecutive patients were studied, comprising: 1095 with wild‐type (wt)ATTR‐CM; 206 with T60A‐hATTR‐CM; and 431 with V122I‐hATTR‐CM. Female prevalence was greater in T60A‐hATTR‐CM (29.6%) and V122I‐hATTR‐CM (27.8%) compared to wtATTR‐CM (6%). At presentation, females were 3.3 years older than males (wtATTR‐CM: 81.9 vs. 77.8 years; T60A‐hATTR‐CM: 68.7 vs. 65.1 years; V122I‐hATTR‐CM: 77.1 vs. 74.9 years). Body size significantly influenced measures of disease severity; when indexed, overall structural and functional phenotype was similar between sexes, the few significant differences suggested a mildly worse phenotype in females. No significant differences were observed in both disease progression on serial echocardiography and mortality across the overall population (p = 0.459) and when divided by genotype (wtATTR‐CM: p = 0.730; T60A‐hATTR‐CM: p = 0.161; V122I‐hATTR‐CM: p = 0.056). Conclusion This study of a well‐characterized large cohort of ATTR‐CM patients did not demonstrate overall differences between sexes in either clinical phenotype, when indexed, or with respect to disease progression and prognosis. Non‐indexed wall thickness measurements may have contributed to both under‐representation and delays in diagnosis for affected females and highlights the potential role of utilizing indexed echocardiographic parameters for a more accurate assessment of patients at diagnosis and for disease prognostication. Deep echocardiographic phenotyping of 1732 patients with ATTR‐CM found no differences in the clinical phenotype between males and females when taking body size into account, with no differences in disease progression on serial imaging and no difference in mortality. Current clinical practice adopts the use of non‐indexed wall thickness measurements, which may have contributed to females being under‐represented, presenting later than males and often with a mildly worse phenotype.