Improved disease-free survival for oral squamous cell carcinoma (SCC) with the use of postoperative radiotherapy (PORT) has to be balanced against the risk of recurrence, the relative morbidity of radiotherapy, reduced options for treatment, and survival with recurrent disease. In the absence of randomised trials, a review of current evidence is timely because of increasing differences in outcome and response to treatment for cancers of the larynx, oropharynx, and oral cavity. From a search of 109 papers, 25 presented relevant data in tabular form, and reported local, regional, and total recurrence, and overall survival. Most data come from non-randomised studies that compared the effects of interventions with previous or historical information. A summary of the results shows local recurrence of 11%, 17%, and 15% for early, late, and all stages after operation alone, compared with 13%, 16%, and 19% after PORT. Regional recurrence is reported as 13%, 12%, and 11% for early, late, and all stages after operation alone compared with 6%, 11%, and 9% after PORT. Overall survival is reported as 76%, 74%, and 77% for operation alone compared with 65%, 62%, and 62% for early, late and all stages of oral SCC, respectively. It is acknowledged that this is a weak level of evidence as patients who have PORT probably have a high pathological-stage of disease. Knowing that PORT increases morbidity and reduces salvage rates and options for treating recurrent disease, this difference in overall survival emphasises the need for randomised studies or a re-evaluation of our current protocols.