Treatments used in cancer of the oral cavity have great impact on the physical, psychological and functional state of patients. There has been increasingly interest in evaluating the health-related quality of life using questionnaires among patients treated with oral cancer. Up to our knowledge no review on this theme has incorporated the level of evidence of the single identified studies. The objective of the present study is to determinate results and conclusions about the health-related quality of life of these patients, in view of scientific evidence. In general, the diversity of designs, level of evidence and questionnaires used for their assessment does not affect results, which indicate a decline in the health related quality of life after treatment. This decline is greater when the tumor is large in size, and when radiotherapy is used, though the situation is seen to improve over the span of a year. Questionnaires on health-related quality of life provide concrete information regarding the impact of cancer treatment on patients.