What is known and objectives Bleeding is the most common adverse reaction to aspirin and can lead to drug discontinuation or even be life‐threatening in the secondary prevention of stroke or transient ischemic attack. The aim of this study was to evaluate risk factors for bleeding adverse reaction of aspirin in ischemic stroke or transient ischemic attack. Methods This retrospective analysis included patients treated with aspirin (100 mg) as a secondary prevention for ischemic stroke or transient ischemic attack. The bleeding events that occurred during the first year were collected, including gastrointestinal, skin, nasal cavity, gum, and urinary tract bleeding events. Then, univariate and multivariate logistic regression analyses were used to identify independent factors associated with bleeding events of aspirin. Results and discussion A total of 578 patients were enrolled in this study, and 58 patients developed bleeding during the first year of secondary prevention. Body weight and combination with selective serotonin reuptake inhibitors were found to be significant risk factors for overall bleeding (p = 0.025 and 0.012). Body weight below 60 kg was a risk factor for overall bleeding and gastrointestinal bleeding events. What is new and conclusion Patients weighing less than 60 kg were at increased risk of bleeding with 100 mg aspirin for secondary prevention of cerebral infarction transient ischemic attack.