Obsessive-compulsive and related disorders (OCRDs), sometimes referred to as obsessive-compulsive spectrum disorders, cause significant impairment and share similar features across several domains, including clinical course, risk factors, and response to treatment. Generally, individuals meeting criteria for one or more OCRDs present with symptoms focused on preoccupations and repetitive behaviors. Sex differences emerge in the clinical presentation of OCRDs, and the associated. Literature emphasizes the importance of considering sex when investigating causal factors, prognosis, and outcomes of OCRDs. Understanding sex-specific phenotypes can help clinicians and healthcare providers to screen for and recognize relevant symptoms, and to create a more tailored approach for care of males and females. In this chapter, we review sex differences in obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), hoarding disorder, trichotillomania (hair-pulling disorder), and excoriation (skin-picking) disorder. Here, we provide an updated review on the sex differences in the prevalence, symptomatology, illness course and prognosis, comorbidity, risk factors, and treatment outcomes associated with OCRDs, and highlight gaps in the current literature on sex differences in these disorders.