Since the approval of the ICD-10 by the World Health Organization (WHO) in 1990, global research on obsessive-compulsive disorder (OCD) has expanded dramatically. This article evaluates what changes may be needed to enhance the scientific validity, clinical utility, and global applicability of OCD diagnostic guidelines in preparation for ICD-11. Existing diagnostic guidelines for OCD were compared. Key issues pertaining to clinical description, differential diagnosis, and specifiers were identified and critically reviewed on the basis of the current literature. Specific modifications to ICD guidelines are recommended, including: clarifying the definition of obsessions (i.e., that obsessions can be thoughts, images, or impulses/urges) and compulsions (i.e., clarifying that these can be behaviors or mental acts and not calling these “stereotyped”); stating that compulsions are often associated with obsessions; and removing the ICD-10 duration requirement of at least 2 weeks. In addition, a diagnosis of OCD should no longer be excluded if comorbid with Tourette syndrome, schizophrenia, or depressive disorders. Moreover, the ICD-10 specifiers (i.e., predominantly obsessional thoughts, compulsive acts, or mixed) should be replaced with a specifier for insight. Based on new research, modifications to the ICD-10 diagnostic guidelines for OCD are recommended for ICD-11.