Head and neck cancer patients being treated with radiotherapy are at an increased risk of malnutrition due to the severe side-effects, e.g. mucositis, odynophagia and xerostomia, impacting on the ability to eat and drink. Effective dietetic management involves identifying those patients malnourished or at risk of becoming so and incorporating nutritional intervention into their treatment plan. The use of gastrostomy tubes in this patient group has been shown to be acceptable. By placing them prophylactically, the aim is to prevent a disruption to treatment and avoid an unnecessary admission for feeding. This audit was carried out to determine whether the implementation of locally produced nutritional guidelines improved the dietetic management of this patient group. A prospective audit tool was used to collect data on 32 head and neck cancer patients undergoing radiotherapy. Data was collected weekly during the course of treatment and compared with data from previous audits. Weight change was the nutritional outcome measured. More patients underwent combined treatment (radiotherapy postoperatively or with concurrent weekly chemotherapy) when compared with previous audits. However, implementation of the guidelines appeared to contribute to an improvement in dietetic management, as fewer patients lost weight over the course of radiotherapy and there were no admissions for feeding. The presence of a dietitian at the multidisciplinary head and neck clinic improved access and communication and this is also likely to have contributed to the improved management. Implementation of the guidelines led to an improvement in the nutritional management of this patient group. Implementation may be more likely if a dietitian is present at the combined head and neck clinic.