Purpose - Whistle-blowing has the important role of reducing the prevalence and impact of wrongdoing in organisations. The purpose of this paper is to utilise a very large survey of Australian Public Service (APS) workers to replicate the findings of previous studies in relation to whistle-blowing likelihood and to extend the quantitative findings in relation to whistle-blowing antecedents to include ethnicity or cultural marginalisation and occupational and professional role and affiliation. Design/methodology/approach - The authors utilise the 2014 APS Census, a large data set containing 100,000 observations relating to employee engagement, leadership, health, satisfaction and general impressions of the public service. Logistic regression is employed to obtain estimates and marginal effects in respect to predictors for whistle-blowing. The authors determine the Bayesian information criterion to assess the impact of ethnicity on the probability of whistle-blowing. Findings - The findings support the notion that organisational "outsiders" tend to report perceived wrongdoing less than those who feel assured of their cultural or organisational status. The authors further find support for the notion that membership of small organisational groupings, primarily measured by organisational size, also tends to reduce the whistle-blowing likelihood. Opportunities for further research and potential policy and practical issues are discussed briefly in conclusion. Originality/value - While confirming the predictors seen in many previous studies, the authors identify groups who report more or less than expected that have not been reported in previous research. These include employees from a non-English speaking background and various occupational and professional groups "at risk" of low reporting.