Clinicians recognize expressive language disturbances in borderline personality disorder (BPD) as a feature attenuating psychiatric history-taking. Neuroimaging studies demonstrate activation of key differentiating neural networks characterizing a traumatic memory system in BPD patients. Yet there are few BPD studies evaluating expressive language disturbances in response to emotionally salient, clinically relevant stimuli and no controlled studies. The aim was to examine expressive language disturbances in response to a clinically relevant emotional stimulus, the Adult Attachment Interview (AAI). Twenty BPD participants and 20 age-, sex-, and education-matched controls were administered the AAI. Verbatim transcripts were analyzed by four computerized measures designed to evaluate various linguistic components of speech (i.e., overall expressive language impairment, lexical complexity, syntactic complexity, and semantic complexity). BPD participants evidenced significantly greater levels of overall expressive language impairment and reduced syntactic and lexical complexity, but not semantic complexity scores. Detailed linguistic profiles demonstrated specific deficits linked to BPD.