Objective Since Australia initiated national open disclosure standards in 2002, open disclosure policies have been adopted in all Australian states and territories. Yet, research evidence regarding their adoption is limited. The aim of the present study was to determine the frequency with which patients who report an adverse event had information disclosed to them about the incident, including whether they participated in a formal open disclosure process, their experiences of the process and the extent to which these align with the current New South Wales (NSW) policy. Methods A cross-sectional survey about patient experiences of disclosure associated with an adverse event was administered to a random sample of 20000 participants in the 45 and Up Study who were hospitalised in NSW, Australia, between January and June 2014. Results Of the 18993 eligible potential participants, completed surveys were obtained from 7661 (40% response rate), with 474 (7%) patients reporting an adverse event. Of those who reported an adverse event, a significant majority reported an informal or bedside disclosure (91%; 430/474). Only 79 patients (17%) participated in a formal open disclosure meeting. Most informal disclosures were provided by nurses, with only 25% provided by medical practitioners. Conclusions Experiences of open disclosure may be enhanced by informing patients of their right to full disclosure in advance of or upon admission to hospital, and recognition of and support for informal or bedside disclosure for appropriate types of incidents. A review of the open disclosure guidelines in relation to the types of adverse events that require formal open disclosure and those more suitable to informal bedside disclosure is indicated. Guidelines for bedside disclosure should be drafted to assist medical practitioners and other health professionals facilitate and improve their communications about adverse events. Alignment of formal disclosure with policy requirements may also be enhanced by training multidisciplinary teams in the process. What is known about the topic? While open disclosure is required in all cases of serious adverse events, patients' experiences are variable, and lack of, or poor quality disclosures are all too common. What does this paper add? This paper presents experiences reported by patients across New South Wales in a large cross-sectional survey. Unlike previous studies of open disclosure, recently hospitalised patients were identified and invited using data linkage with medical records. Findings suggest that most patients receive informal disclosures rather than a process that aligns with the current policy guidance. What are the implications for practitioners? Experiences of open disclosure may be enhanced by informing patients of their right to full disclosure in advance of or upon admission to hospital, and recognition of and support for informal or bedside disclosure for appropriate types of incidents.