Recently, it has been suggested that a direct assessment of left ventricular (LV) mechanical dyssynchrony may improve the selection of candidates to cardiac resynchronization therapy (CRT). In fact, when the established clinical and electrocardiographic selection criteria are applied, response to CRT may vary widely and up to one-third of the patients fail to benefit from CRT. Echocardiography has been extensively applied to assess LV dyssynchrony and to predict favourable response to CRT, using different two- and three-dimensional modalities. In this review, the value of these echocardiographic modalities will be discussed, highlighting the advantages and drawbacks of each technique and evaluating the clinical implications and future perspectives of LV dyssynchrony assessment.