The authors present their experience in ultrasound patterns of primary and recurrent endometrioma and correspondence with histopathological results, using 2D and color Doppler ultrasound examination. Cases of primary and recurrent endometriomas, as well as other false positive diagnosis are presented. The presence of the peripheral, healthy ovarian tissue, is the principal difference between the primary endometrioma and their recurrence. The arousal of papillary projections or solid-type echostructure decreases the likelihood of an endometrioma without histological atypia. Postmenopause modifies the ultrasound features of endometrioma by decreasing homogeneity and echogenicity.