Background The aim of this paper is to understand the process of information disclosure and privacy as patients share their news of lung cancer with significant others. Methods Twenty patients with lung cancer and 17 family members/friends accompanying them at diagnosis‐giving completed either individual or dyad semi‐structured interviews. Initial thematic analysis, then Petronio's Communication Privacy Management theory was used to inform interpretation. Results Patients described a sense of ownership of the news of their cancer and sought control of how, when and with whom it was shared. Family members expressed a need to follow the patients' rules in sharing this news, which limited their own support systems. Patients and family members had to live within the relational communication boundaries in order to maintain their trusting relationship and avoid potential disruptions. Conclusion Patients as individuals are strongly interlinked with significant others, which impacts on their experience of disclosing private information. This shapes their psychological processes and outcomes impacting on their illness experience. This should be considered when developing interventions to support patients with sharing bad news. Copyright © 2015 John Wiley & Sons, Ltd.