Errors are frequent in health care. A specific model was tested that affirms failure in cognitive action regulation to mediate the influence of nurses' workflow interruptions and safety conscientiousness on near-accidents in health care. One hundred and sixty-five nurses from seven Swiss hospitals participated in a questionnaire survey. Structural equation modelling confirmed the hypothesised mediation model. Cognitive failure in action regulation significantly mediated the influence of workflow interruptions on near-accidents (p < .05). An indirect path from conscientiousness to near-accidents via cognitive failure in action regulation was also significant (p < .05). Compliance with safety regulations was significantly related to cognitive failure and near-accidents; moreover, cognitive failure mediated the association between compliance and near-accidents (p < .05). Contrary to expectations, compliance with safety regulations was not related to workflow interruptions. Workflow interruptions caused by colleagues, patients and organisational constraints are likely to trigger errors in nursing. Work redesign is recommended to reduce cognitive failure and improve safety of nurses and patients.