Although the incidence and clinical manifestations of pituitary apoplexy were reported by a few researches, the results are not consistent. This study aimed to explore the risk factors associated with an incidence of apoplexy in pituitary adenomas.The clinical information of 843 patients with pituitary adenoma from the Department of Neurological Surgery, 1st Affiliated Hospital of Kunming Medical University, was reviewed. The incidence, clinical manifestation, and potential risk factors for pituitary apoplexy were analyzed by a case-control study.In total, 121 patients (14.4%) with macroadenoma were suffered from pituitary apoplexy. Headache, vomiting, and visual impairment are the top 3 symptoms for the pituitary apoplexy.Logistic regression results showed that the hypertension(hypertension vs non-hypertension OR = 2.765, 95%CI:1.41~5.416), tumor type (negative staining vs. positive staining, OR = 1.501, 95%CI:1.248~5.235), and tumor size (diameter > 2 cm vs. diameter ≤ 2 cm, OR = 3.952, 95%CI:2.211~7.053) are independent factors associated with pituitary apoplexy.Our results indicate that the risk factors for the incidence of pituitary apoplexy depend mainly on properties of the tumor itself (tumor size and pathologic type) and the blood pressure of patients.© The Author(s) 2020.