Three case reports of patients with borderline personality disorder (BPD) and obsessive-compulsive disorder (OCD) for more than 10 years are used to illustrate the relationship between OCD and borderline pathology.

The recognizable features of the obsessive-compulsive symptoms in these reports are :

• (i) pervasiveness, the symptomatic overlap of obsessive-compulsive symptoms ;

• (ii) poor insight and resistance ;

• and (iii) obsessive control evident in personal relationships.

These features are manifestations of OCD psychopathology as well as of a personality disorder.

The symptoms with these features are located hypothetically towards the severe end of the symptomatic spectrum of OCD.

The comorbidity is not a simple relationship, and the symptomatology of the comorbid patient is derived from OCD pathology linked with the personality disorder rather than from independent BPD pathology.