Surgical treatment of the oral and oropharyngeal cancer is accompanied by occurrence of extensive defects and dysfunctions of swallowing, voice, and speech. These patients are one of the most difficult contingents for medical rehabilitation. Criteria with a gradation by functional classes for an objective clinical and expert assessment of functional disorders have been developed. They are based on adaptation of the International Classification of Functioning, Disability and Health (ICF) concepts and use of simple diagnostic tests. Application of these criteria during special treatment will make it possible to develop an individual program of early medical rehabilitation and for monitoring the rehabilitation effectiveness, evaluate the effectiveness, and make decisions on the timely correction of developing functional disorders.