Borderline personality disorder (BPD) is a valid and reliable diagnosis with effective treatments. However, data suggest many patients remain unaware they carry the diagnosis, even when they are actively engaged in outpatient psychiatric treatment. The authors conducted a survey of 134 psychiatrists practicing in the United States to examine whether they had ever withheld and/or not documented their patients’ BPD diagnosis. Fifty-seven percent indicated that at some point during their career they failed to disclose BPD; 37 percent said they had not documented the diagnosis. For those respondents with a history of not disclosing or documenting BPD, most agreed that either stigma or uncertainty of diagnosis played a role in their decisions. The findings highlight the need for clinical training programs to address these issues. The research also invites further research to identify other reasons why psychiatrists are hesitant to be fully open about the diagnosis of BPD.