Background Despite uncertainty regarding the benefits of prostate cancer screening, many men have had a prostatespecific antigen (PSA) test. Purpose This study aims to identify classes of reasons guiding men's decisions about prostate cancer screening and predict reasoning approaches by family history and prior screening behaviour. Methods First-degree relatives of men with prostate cancer (n=207) and men from the general population (n=239) of Australia listed reasons they considered when deciding whether to have a PSA test. Results Responses were coded into 31 distinct categories. Latent class analysis identified three classes. The evaluation of risk information cues class (20.9 %) contained a greater number of men with a family history (compared with control and overcome cancer/risk class; 52.7 %). Informed decisions and health system class (26.5 %) included a lower proportion of men who had had a PSA test and greater proportions of highly educated and married men. Conclusion Understanding the reasons underlying men's screening decisions may lead to a more effective information provision and decision support.