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Introduction Basilar artery perforator aneurysms (BAPAs) are a rare but increasingly recognized subtype of intracranial aneurysms. Their natural history remains poorly understood, and treatment strategies vary considerably.Aim of study To better characterize the clinical presentation, management approaches, and outcomes of BAPAs, the multicenter PERFAN (Perforator Aneurysm) registry—endorsed by the European Society of Minimally Invasive Neurological Therapy (ESMINT)—was initiated in 2023.Method Participating centers retrospectively identified patients presenting with a perimesencephalic subarachnoid hemorrhage due to a BAPAs. Clinical data, aneurysm morphology, treatment modalities, and outcomes were collected and analyzed.Results A total of 148 patients with BAPAs were included (mean age 58.3 ± 11.7 years; 59% male). Of these, 83 patients (44%) underwent active treatment, predominantly endovascular, while 65 patients (56%) were managed conservatively. The median aneurysm size in the actively treated group was 2.0 mm (IQR 1.27–3.03), compared to 1.2 mm (IQR 1.0–3.0) in the conservatively managed group (p < 0.001).At 3–6 months follow-up, excellent clinical outcomes (modified Rankin Scale [mRS] 0–1) were observed in 82% of conservatively managed patients, compared to 60% in the actively treated group (p = 0.018).Conclusion The PERFAN registry represents the largest cohort of BAPA patients to date and provides valuable insights into their management. The findings suggest that conservative treatment may be associated with more favorable short-term outcomes, while active intervention carries a higher risk of morbidity. These results highlight the need for a prospective study to guide evidence-based treatment decisions for this rare aneurysm subtype.Conflict of Interest No