Isolated unilateral pleural effusion is uncommon presentation of ovarian hyperstimulation syndrome. The pathogenesis of this syndrome involves an increased permeability of ovarian capillaries and mesothelial vessels triggered by the release of vasoactive substances by the ovaries under human chorionic gonadotropin stimulation. Physicians should consider this potentially life-threatening diagnosis in all patients who undergo ovarian hyperstimulation. This case highlights a rare clinical manifestation of isolated hemorrhagic pleural effusion associated with ovarian hyperstimulation