Diverticula of the urinary bladder can occasionally appear as complex pelvic masses not obviously connected to the bladder. Such presentations can lead to diagnostic confusion and interpretative error. Sonographic findings and clinical histories were reviewed in 11 patients in whom bladder diverticula were initially mistaken for other types of pathologic pelvic processes. Sonographic techniques that were helpful in elucidating the true nature of the lesions included scanning from different perspectives with increasing increments of bladder distention, postvoid images, endovaginal views, and color Doppler interrogation. The diagnosis of bladder diverticula should be considered and actively pursued when sonologists are confronted with pelvic masses of ambiguous origin.