BACKGROUND: Currently used pre-operative prediction scores for postoperative pulmonary complications (PPCs) use patient data and expected surgery characteristics exclusively. However, intra-operative events are also associated with the development of PPCs. OBJECTIVE: We aimed to develop a new prediction score for PPCs that uses both pre-operative and intra-operative data. DESIGN: This is a secondary analysis of the LAS VEGAS study, a large international, multicentre, prospective study. SETTINGS: A total of 146 hospitals across 29 countries. PATIENTS: Adult patients requiring intra-operative ventilation during general anaesthesia for surgery. INTERVENTIONS: The cohort was randomly divided into a development subsample to construct a predictive model, and a subsample for validation. MAIN OUTCOME MEASURES: Prediction performance of developed models for PPCs. RESULTS: Of the 6063 patients analysed, 10.9% developed at least one PPC. Regression modelling identified 13 independent risk factors for PPCs: six patient characteristics [higher age, higher American Society of Anesthesiology (ASA) physical score, pre-operative anaemia, pre-operative lower SpO2 and a history of active cancer or obstructive sleep apnoea], two procedure-related features (urgent or emergency surgery and surgery lasting ≥ 1 h), and five intra-operative events [use of an airway other than a supraglottic device, the use of intravenous anaesthetic agents along with volatile agents (balanced anaesthesia), intra-operative desaturation, higher levels of positive end-expiratory pressures > 3 cmH2O and use of vasopressors]. The area under the receiver operating characteristic curve of the LAS VEGAS risk score for prediction of PPCs was 0.78 [95% confidence interval (95% CI), 0.76 to 0.80] for the development subsample and 0.72 (95% CI, 0.69 to 0.76) for the validation subsample. CONCLUSION: The LAS VEGAS risk score including 13 peri-operative characteristics has a moderate discriminative ability for prediction of PPCs. External validation is needed before use in clinical practice.