Anastomotic leak (AL) is the most serious early complication after esophagectomy and significantly impacts treatment outcomes. The aim of this study is to review the current principles of diagnosis and management of AL using standardized definitions and classifications and the “step-up” approach. The key factors in diagnosis are a high index of clinical suspicion, computed tomography of the chest and abdomen with oral water contrast as the first-choice examination and early endoscopy, which combines a diagnostic role with the possibility of immediate therapy. The “step-up” approach involves rapid control of sepsis and source of infection (radiologic or surgical drainage), gastrointestinal decompression (nil per os), targeted antibiotic therapy and preferably enteral nutrition, with escalation to endoscopic treatment. Depending on the local findings, covered self-expanding metal stents or self-expanding plastic stents, endoscopic vacuum therapy (EVT), and – in selected situations – endoscopic internal drainage are used. In cases of extensive tissue damage, conduit necrosis, or failure of endoscopic therapy, surgical treatment may be required. Combined strategies (e.g. sequential EVT → stent) and hybrid solutions (stents with integrated vacuum systems) allow the therapy to be tailored to local conditions. Effective implementation of coordinated protocols in experienced centers, with the involvement of a multidisciplinary team, is associated with a decrease in mortality and improved short- and long-term outcomes.