BACKGROUND Cerebral amyloid angiopathy (CAA) results from progressive deposition of amyloid-ß in the walls of cortical and leptomeningeal vessels, leading to CAA-associated intracerebral hemorrhage (ICH). Hematoma expansion is a common early complication of spontaneous ICH, and is a strong independent predictor of poor outcome. However, there are limited reports of hematoma expansion related to CAA-associated ICH. Herein, we describe a novel case of hematoma expansion with a fluid-blood level in the cystic cavity of CAA-associated ICH. CASE REPORT A 76-year-old male was initially diagnosed with probable CAA according to the modified Boston criteria, and presented with lobar ICH in the left frontal lobe 4 months later. Admission computed tomography scans showed an ICH including a high-density hematoma within a cystic cavity, revealing a clearly lower-density fluid component. Serial computed tomography scans showed no evidence of an expansion of the high-density clot, but obvious expansion of the fluid component containing a fluid-blood level. We recognized a bleeding site with no enhancement on preoperative magnetic resonance imaging. Left frontal craniotomy revealed a liquefied hematoma, which was removed by suction. We subsequently evacuated the blood clot extending into the left frontal sulcus, and confirmed and cauterized the bleeding site, leading to successful hemostasis. CONCLUSIONS We report a CAA-associated ICH case showing hematoma expansion with a fluid-blood level. Intraparenchymal fluid-blood level suggests extravasation of blood into pre-existing cystic cavities because of hematoma liquefaction. Thus, fluid-blood levels are an important finding of hematoma expansion in acute CAA-associated ICH, and early treatment should be considered.