Context: This study was part of the Methods of Assessing Response to Quality Improvement Strategies (MARQulS) research project on patients crossing borders, a study to investigate quality improvement strategies in healthcare systems across the European Union (EU). Aim: To explore the association between the implementation of quality improvement strategies in hospitals and hospitals' success in meeting defined quality requirements that are considered intermediate outputs of the care process. Methods: Data regarding the implementation of seven quality improvement strategies (accreditation, organisational quality management programmes, audit and internal assessment of clinical standards, patient safety systems, clinical practice guidelines, performance indicators and systems for obtaining patients' views) and four dimensions of outputs (clinical, safety, patient-centredness and cross-border patient-centredness) were collected from 389 acute care hospitals in eight EU countries using a web-based questionnaire. In a second phase, 89 of these hospitals participated in an on-site audit by independent surveyors. Pearson correlation and linear regression models were used to explore associations and relations between quality improvement strategies and achievement of outputs. Results: Positive associations were found between six internal quality improvement strategies and hospital outputs. The quality improvement strategies could be reasonably subsumed under one latent index which explained about half of their variation. The analysis of outputs concluded that the outputs can also be considered part of a single construct. The findings indicate that the implementation of internal as well as external quality improvement strategies in hospitals has beneficial effects on the hospital outputs studied here. Conclusion: The implementation of internal quality improvement strategies as well as external assessment systems should be promoted.