Background: The Comprehensive International Classification of Functioning, Disability and Health (ICF) Core Set for Multiple Sclerosis (MS) is a comprehensive framework to structure the information obtained in multidisciplinary clinical settings according to the biopsychosocial perspective of the International Classification of Functioning, Disability and Health (ICF) and to guide the treatment and rehabilitation process accordingly. It is now undergoing validation from the user perspective for which it has been developed in the first place. Aims: To validate the content of the Comprehensive ICF Core Set for MS from the perspective of speech and language therapists (SLTs) involved in the treatment of persons with MS (PwMS). Methods & Procedures: Within a three-round e-mail-based Delphi Study 34 SLTs were asked about PwMS' problems, resources and aspects of the environment treated by SLTs. Responses were linked to ICF categories. Identified ICF categories were compared with those included in the Comprehensive ICF Core Set for MS to examine its content validity. Outcomes & Results: Thirty-four SLTs named 524 problems and resources, as well as aspects of environment. Statements were linked to 129 ICF categories (60 "Body-functions" categories, two "Body-structures" categories, 42 "Activities & participation" categories, and 25 "Environmental-factors" categories). SLTs confirmed 46 categories in the Comprehensive ICF Core Set. Twenty-one ICF categories were identified as not-yet-included categories. Conclusions & Implications: This study contributes to the content validity of the Comprehensive ICF Core Set for MS from the perspective of SLTs. Study participants agreed on a few not-yet-included categories that should be further discussed for inclusion in a revised version of the Comprehensive ICF Core Set to strengthen SLTs' perspective in PwMS' neurorehabilitation.