Objective To explore the clinical features of perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH).Methods A retrospective analysis was performed on 27 patients with PNSAH admitted to our department from January 2007 to January 2017 to investigate their clinical manifestations and imaging findings, as well as the diagnosis and treatment of PNSAH.Results All the 27 patients had negative results on the first whole-brain digital subtraction angiography (DSA), and also had negative results on DSA or computed tomography angiography of the brain performed two weeks later. All the patients had a benign course of disease during hospitalization, with a mean length of hospital stay of 13.5±3.2 days. Follow-up was performed for 7 months to 10 years (mean 5.2±3.1 years), and no rebleeding or focal neurological deficit was found.Conclusions PNSAH is a special type of SAH with a benign course and a good prognosis, and has few complications and sequelae; however, the diagnostic criteria for PNSAH should be strict in clinical practice.