In this paper a case of severe obsessive-compulsive disorder is presented. The patient had alcohol abuse, narcissistic personality disorder and paranoid personality disorder as comorbid conditions. Assessment included Yale-Brown Obsessive-Compulsive scale, Millon Clinical Multiaxial Inventory (second edition), and International Personality Disorders Examination. The psychological treatment was based on cognitive-behavioral and strategic family therapy. The treatment lasted four years and was tailor-made administered. Due to the lack of the patient’s collaboration, the alcohol abstinence and the obsessive-compulsive symptoms were initially treated by means of paradoxical interventions and other strategic family techniques. After obtaining the patient’s collaboration, exposure with response prevention was employed to address the obsessive-compulsive symptoms. These Axis I symptoms were reduced in a clinically significant degree. Paranoid and narcissistic symptoms were treated on the basis of cognitive therapy (Beck and Freeman, 1995) but the clinical change was small. Relations between narcissistic personality disorder, paranoid personality disorder, obsessive-compulsive disorder and their influence in the response to psychological treatment are discussed.