Left ventricular hypertrophy is a common complication of different diseases. Among these, cardiac involvement of amyloidosis or Anderson-Fabry disease are often unrecognized. Early diagnosis is therefore crucial because new therapies can impact the progression of these diseases. Different specific signs unmasked by clinical, laboratory, and non-invasive diagnostic tests such as echocardiography or cardiac magnetic resonance could guide clinicians towards an appropriate diagnosis. The aim of this review is to underline the major diagnostic clues of different forms of left ventricular hypertrophy in adult patients, guiding clinicians towards a more appropriate diagnosis.