Gastrointestinal endoscopic procedures include esophagogastroduodenoscopy, colonoscopy, percutaneous endoscopic gastrostomy, endoscopic retrograde cholangiopancreatography and endoscopic ultrasound. Mentioned invasive methods that visualize individual parts of the digestive system, carry a certain risk of adverse events. Using modern devices and more advanced techniques, the risk of complications has significantly decreased compared to the beginnings of their application. Preparing the patient before performing a particular procedure is extremely important for the procedure to be successful, but also to minimize the risk of complications. The main and most common complications of all gastrointestinal endoscopic procedures are perforation and bleeding. Regardless of the type of technique, the existing coagulopathy or the use of anticoagulant drugs increases the risk of bleeding, while perforation is contributed by poor preoperative preparation, pathology of the wall of the digestive system as well as performing therapeutic endoscopy procedures. The choice of treatment modalities depends on the severity of the complication and the health status of the patient. It may include the use of conservative therapy, repeated endoscopic techniques and in the most severe conditions, emergency surgery. Endoscopists must thus keep in mind the possibility of common complications, but also those that are extremely rare and specifically related to a particular technique. Some of possible specific complications are splenic injury and post-polypectomy syndrome associated with colonoscopy, the occurrence of post-ERCP pancreatitis after ERCP and buried bumper syndrome with the use of PEG. Finally, infectious complications, side effects of intravenous sedation or anesthesia as well as cardiovascular complications are possible with these invasive methods as well as any other procedure. Thorough preoperative treatment and careful monitoring during the procedure should minimize these adverse events.