This article examines the conceptualization of prison officers as psychologically ‘dirty’. It defines the novel ‘psychological taint’ and taint management strategies in their occupational cultures. Drawing on ethnographic data, psychological taint’s three sources are identified as the psychological processes necessary to do their job, contamination through association with groups stigmatized as mentally unwell, and the pernicious effects of prison work. The article analyses the relationship between unaddressed anxiety provoked in prison work and the amplified salience of external threat in psychological taint. While advancing studies of occupational cultures and identities, psychological taint offers a constructive lens to analyse occupations across multiple fields. The presented implications address the nature of prison workplaces, punishment and the provision of mental health supports.