The concept of field changes by carcinogens within the upper aerodigestive tract is well established with reported rates of synchronous tumours of 4% and second primaries of 36%. The tonsil in particular has the highest rate of synchronous tumours, postulated as being due to a broad based, high surface-area contact point for carcinogens, such as tobacco smoke and HPV. However preoperative PET-CT can struggle to identify tonsillar tumours due to increased cellular metabolism in this tissue. This is the first paper to look specifically at the rate of bilateral tonsillar cancer in the setting of a unilateral known tonsillar carcinoma. The proposed added morbidity and complications from the additional contralateral tonsil dissection is the argument this group wanted to challenge with this retrospective comparative non-randomised study. This paper reports the outcomes of 79 consecutive patients all undergoing surgery for T1-T3 biopsy proven unilateral tonsillar SCC using radical tonsillectomy with transoral robotic surgery and neck dissection, with no radiological or pan-endoscopy evidence of malignancy in the contralateral tonsil. Thirty patients also had contralateral tonsillectomy as was standard of care by their operating surgeon. From this group, 10% (n = 3) had carcinoma in the contralateral tonsil, and went on to have bilateral rather than ipsilateral radiotherapy postoperatively. Complications and functional outcomes were the same in both groups, apart from a clinically negligible increased blood loss of 12 cc in the bilateral tonsillectomy group. The conclusion drawn is that the low added morbidity of performing a contralateral tonsillectomy may increase the pick-up rate of synchronous tumours, particularly in the era of HPV-positive disease.