Primary acute convexity subarachnoid hemorrhage (cSAH) in older patients can be observed in cerebral amyloid angiopathy (CAA) or idiopathic (with cSAH as potential initial manifestation of suspected CAA). We aimed to analyze baseline, clinical and MRI (including quantitative cSAH surface analysis and topographical probabilistic cSAH mapping) characteristics in elderly cSAH patients with CAA. Materials and methods: Baseline/clinical/MRI characteristics of 50 consecutive primary acute cSAH patients ≥ 55 years with suspected/possible/probable CAA were retrospectively analyzed. Results: Median age was 74, with 26% of patients showing suspected, 22% possible and 52% probable CAA. Transient focal neurological episode (TFNE) was observed in 78%, with spreading symptoms in 79% (median spreading speed five minutes), a median of two episodes before cSAH diagnosis, and similar symptoms in 91% when multiple TFNE, with a median duration of 15 min. Motor/sensory/speech/visual symptoms were observed in 85%/69%/46%/8%, respectively, and brachiofacial/brachial was the most frequent distribution for sensory-motor symptoms. Positive clinical-radiological correlation was observed in 84%, headache in 22%, and antiepileptics started in 78%. MRI showed chronic intracerebral hemorrhage in 10%, cortical superficial siderosis in 68%, cerebral microbleeds in 48%, median total Fazekas score of 3, lacunes in 6% and DWI lesion (all unique/cortical/ < 10 mm) in 6%. cSAH involved a median of 1 sulcus, with central sulcus as most frequently (47.5%) involved followed by precentral sulcus (17%). Median cSAH surface was 2170 mm2. No baseline, clinical or MRI characteristics were associated with cSAH surface extent in multivariate analysis. Conclusions: Baseline, clinical, or MRI features seem not to influence CAA-related cSAH extent.