Research suggests that a significant proportion of inpatients in general medical wards may lack capacity to make treatment decisions, a situation that often goes unrecognised by clinicians. We would like to briefly discuss two cases from a non-psychiatric setting, where a mental disorder served to inhibit the individual's ability to weigh-up associated risks when deciding to refuse potentially life-sustaining healthcare interventions. In both cases the history of mental disorder was well established yet, for markedly different reasons, the respective presentation was such that the influence of the disorder on decision-making was not evident to the treating teams.