BACKGROUND: Insecure attachment style has been associated with obsessive-compulsive disorder (OCD). Psychological stress is known to aggravate OCD symptoms and activate the attachment system. Here, we investigated reactivity of attachment-related neurocircuitry under psychological distress in OCD patients. METHODS: Twenty-two patients with OCD and twenty-three healthy controls underwent fMRI scanning after psychological stress induction and a control condition in a cross-over design. Neural responses were measured during presentation of negative emotional faces. Attachment insecurity was measured using the self-report experiences in close relationships scale (ECR) and the adult attachment interview (AAI). RESULTS: OCD participants showed higher scores on ECR attachment anxiety compared to controls. Stress was successfully induced as shown by subjective stress measurements and physiological parameters. OCD participants showed a blunted cortisol response to the stressor. However, no group differences were found in neural stress responses. Across participants, psychological distress decreased hippocampal responses. This effect was dependent on attachment style, with participants scoring high on attachment anxiety showing increased rather than decreased hippocampal activity when distressed. Participants scoring high on attachment insecurity as measured with the AAI showed increased activity in multiple attachment-related brain regions. CONCLUSIONS: Attachment style, but not OCD status, modulated neural responses to emotionally salient information under psychological distress. These findings provide further support for the assumption that attachment insecurity may be an important transdiagnostic vulnerability factor.