This document provides an overview of obsessive-compulsive disorder (OCD) and its treatment using cognitive-behavioral therapy and brief strategic therapy. It begins with definitions of OCD according to the DSM-5 and ICD-10 diagnostic criteria, and then provides an operative diagnosis description of OCD according to brief strategic therapy. This involves how OCD forms as an overwhelming need to check reality through compulsive rituals and thoughts. The document goes on to describe the paradigms and treatment approaches of cognitive-behavioral therapy and brief strategic therapy for OCD. It concludes with case studies demonstrating brief strategic therapy treatment.