High-output leaks of the upper gastrointestinal wall (more than 500 ml/24 h) are followed by a high mortality rate. Immediately rising catabolism and generalized peritonitis after spread of the intestinal content throughout the peritoneal cavity are the main reasons. An exclusively conservative treatment as well as radical surgical resections are not successful. Therefore, we have developed a two-step management in our clinic. The first step is a conservative treatment with parenteral hyperalimentation and local therapy of peritonitis. The second step – the definite closure of the enterocutaneous fistula – was performed after the stage of peritonitis and catabolism, as a rule after 2 or 4 weeks. Due to long periods of pretreatment, the treatment of our patients lasted 63.4 days on average. Improvement of treatment time is possible with early interventional opening of the fistulas. With the two-step management a closure of 90% of enterocutaneous fistulas of the upper gastrointestinal tract was achieved.