We retrospectively analysed the incidence of symptomatic venous thromboembolism (VTE) and associated risk factors in operations under general anaesthesia for cancer of the oral cavity. To identify symptoms related to deep venous thrombosis (DVT) and pulmonary embolism (PE), together with associated risk factors, we reviewed medical records of patients operated on in the department of oral and maxillofacial surgery at the Queen Elizabeth Hospital, Birmingham, United Kingdom, between June 2007 and October 2012. All patients were categorised according to their level of risk of VTE. The incidence of VTE was calculated with univariate associations and odds ratios with related 95% confidence intervals, where possible. In total, 233 patients were included, comprising 244 operations (mean (SD) age at operation 60.9 (13) years). Almost all patients (97%) were classified as having the highest risk of VTE. Swelling of an extremity, expectoration of blood, and tightness of the chest were the most common symptoms for suspected cases. An incidence of 0.41% was found for symptomatic VTE; one man developed a PE 2 days after operation. Associations between the analysed factors and symptomatic VTE were not significant. The development of the complication in oncological oral and maxillofacial operations seems to be rare, even in patients with a high risk. We cannot recommend the use of routine thromboprophylaxis, but it could be advocated in patients with obvious serious risk factors.