Pathological narcissism is characterized by impaired interpersonal functioning, but few studies have examined the impact of the disorder on those living in a close relationship. Participants (N = 683; comprising romantic partners [77.8%], mothers [8.5%] or other family members [10%]) in a close relationship with a relative with pathological narcissism completed measures assessing levels of grief, burden, mental health, and coping style. Participants’ reported burden was over 1.5 standard deviations above comparison carers of people with mood, neurotic, or psychotic disorders, and higher than carers of people with borderline personality disorder. Similarly, caseness for depression (69% of sample) or anxiety disorders (82%) in the sample was high. Relationship type, subtype expression (vulnerable/grandiose), and coping style were all found to significantly relate to experienced psychopathology. Although limitations exist regarding sample selection that may influence interpretation of results, these findings quantify the significant interpersonal impact of pathological narcissism in this sample.