Incidence and type of postoperative complications were prospectively analyzed in 2280 patients undergoing gastrointestinal surgery. 6.6% had one or more pulmonary complications requiring therapeutic intervention (2.3% pneumonia, 1.6% drained pleural effusions, 1.2% atelectases). Based on univariate and logistic regression analyses, the following parameters constitute high-risk patients with regard to pulmonary complications: Elective surgery (4.3%, 61/1428): anemia (7.2% pulmonary complications), pathological blood gas analysis (9.8%), preoperative hospitalization greater than 1 week (6.3%), blood loss under operations greater than 1000 ml (10.5%), length of the operation greater than 3 h (9.7%); emergency surgery (10.4%, 89/852): upper gastrointestinal operation (16.2%), age greater than 75 (19.9%), ASA IV/V (28%), anemia (19.6%), chronic bronchitis (19%), pathological blood gas analysis (26.6%), diabetes (16.5%), heart failure (18.2%), blood loss under operation greater than 1000 ml (24.3%), length of the operation greater than 2 h (15.4%). These results allow to distinguish between different levels of pulmonary risk.