Endometriosis and adenomyosis may be accurately diagnosed using ultrasound (US). Several findings are characteristic and various US modalities have been described. Recent development of 3-dimensional transvaginal US has resulted in a major advance in the evaluation of adenomyosis. Endometriotic manifestations can also be accurately evaluated with US, which is and should remain the first-line approach for the evaluation of these conditions. Obvious advantages over magnetic resonance imaging include its wide-availability, tolerability, less time-consumption, more accessible price and familiarity of gynecologists with its use. This technology’s full potential can be achieved using 3-dimensional imaging and/or modified techniques according to the particular clinical scenario.