Resumen: The aim of the study is to describe the therapeutic process and identify the therapeutic foci in psychoanalytic psychotherapy sessions with a patient with borderline personality disorder (BPD). A mixed and longitudinal approach was used, based on Systematic Case Study. The Psychotherapy Process Q set (PQS) was used to characterize and describe the therapeutic process. The Operationalized Psychodynamic Diagnosis (OPD-2) identified the therapeutic focus of the sessions and established the psychodynamic diagnosis. The results showed changes in structure and strengthening in two structural functions: impulse management regulation and differentiation of ego objects. The OPD pointed out work was directed at structure, concluding that a greater therapeutic focus on structure seems to be more appropriate for these patients. The study shows that the integration of these two methods sheds light on what happens in the treatment, what the mental states and the priority issues are, and how the therapeutic work is focused, as well as its relationship with the basic structure.