A 46 year-old man with acquired immunodeficiency syndrome presented with sudden development of vertigo and tinnitus and then simultaneous, bilateral, profound, sudden hearing loss. Magnetic resonance imaging showed bilateral high signal within the cochlea, vestibule, and portions of the semicircular canals on the non-enhanced T1-weighted images, most consistent with recent hemorrhage into the otic labyrinth. Serum analysis and bone-marrow biopsy led to diagnosis of Waldenstrom's macroglobulinemia - a likely cause of the presumed hemorrhage.