A review of histologic classification systems for grading of malignancy in squamous cell carcinomas of the head and neck region is presented. Reasons behind the varying results obtained in studies using histomorphologic grading schemes are presented and potential errors involved in this type of clinical research are discussed. Requirements for the study of correlations between malignancy grade scoring, and recurrence and survival rates are presented. These include factors as patient selection, clinical staging, and follow-up principles. Special attention must be given to treatment modalities, establishment of negative surgical margins and occurrence of regional lymph node and/or distant metastases.