[en] Objective To assess whether the Belgian Hospital Discharge Dataset (B-HDDS) is a valid source for the detection of adverse events in acute hospitals. Design, setting and participants Retrospective review of 1515 patient records in eight acute Belgian hospitals for the year 2005. Main outcome measures Predictive value of the B-HDDS and medical record reviews and degree of correspondence between the B-HDDS and medical record reviews for five indicators: pressure ulcer, postoperative pulmonary embolism or deep vein thrombosis, postoperative sepsis, ventilator-associated pneumonia and postoperative wound infection. Results Postoperative wound infection received the highest positive predictive value (62.3%), whereas postoperative sepsis and ventilator-associated pneumonia were rated as only 44.2% and 29.9% respectively. Excluding present on admission from the screening substantially decreased the positive predictive value of pressure ulcer from 74.5% to 54.3%, as pressure ulcers present on admission were responsible for more B-HDDS-medical record mismatches than any other indicator. Over half (56.8%) of false-positive cases for postoperative sepsis were due to a lack of specificity of the ICD-9-CM code, whereas in 58.6% of false-positive cases for ventilator-associated pneumonia, clinical criteria appeared to be too stringent. Conclusions The B-HDDS has the potential to accurately detect some but not all adverse events. Adding a code 'present on admission' and improving the ICD-9-CM codes might already partially improve the correspondence between the B-HDDS and the medical record review.