The problem of co-occurrence of alcohol use disorders and personality disorders seems to be crucial from both the clinical and the therapeutic perspective. The co-occurrence rate is high and amounts to about 60% in clinical groups and about 29% in the non-clinical group. Despite the significant co-occurrence of alcohol use disorder and personality disorders, the nature of the relationship between these two is still vaguely known. All the more reason to acknowledge that the research on the above-mentioned relationship is significant and can lead to a better understanding of patients with dual diagnosis as well as to the optimisation of psychotherapeutic interventions directed at those patients. The article presents a case study of a patient with diagnosed alcohol use disorder and mixed personality disorders (borderline personality disorder, narcissistic personality disorder) and an attempt to understand the mutual dependence of these disorders in the context of the patient’s life story, including the history of numerous treatment attempts. The case conceptualisation has been based on the psychodynamic paradigm referring to O. F. Kernberg’s model of personality pathology as well as other psychodynamic concepts which directly address the issue of psychoactive substances abuse.