Breath test and gastroscopy are both gastric examinations can assist in the diagnosis of gastric diseases, there is generally no clear order of priority between the two. Gastroscopy is an invasive examination, requiring patients to fast for 6 to 8 hours before the examination, fasting and water on the day of the examination, in order to prepare the stomach for the observation of the doctor, the examination can also take biopsy of the suspected site for pathological examination. Breath test includes carbon 13 or carbon 14 breath test experiment, which requires the patient to swallow a urea capsule containing carbon 13 or carbon 14 labeling before the examination, sit quietly for about half an hour, and collect the exhaled gas to check whether Helicobacter pylori infection. The breath test is a non-invasive test, but requires fasting. There is no clear requirement as to which should be done first, the breath test or the gastroscopy. The medication and water swallowed during the breath test are usually small and do not significantly affect the gastroscopy, and the gastroscopy usually does not affect the results of the breath test, so there is no specific order of precedence between the two. If they are done at the same time, because gastroscopy requires the application of local anesthetics, and water can only be consumed about 30-60 minutes after gastroscopy, the breath test can be done first to save waiting time. Patients are advised to consult their doctors in advance before performing the breath test and gastroscopy, and to rationally arrange the tests and decide on the order of precedence under the doctor’s guidance.