Background: Treatments for cancer can cause a range of oral side effects which can compromise patientsâ€™ quality of life and even their chances of survival. The evidence for the prevention of some of these side-effects, primarily oral mucositis and salivary gland dysfunction, is often scarce or conflicting. Such evidence is needed to support the recommendations given in clinical guidelines. Aims: (i) To assess the effects of interventions for preventing oral mucositis in patients with cancer who are receiving treatment; (ii) To assess the effects of pharmacological interventions for the prevention of radiation-induced salivary gland dysfunction; (iii) To assess the quality of guidelines on the management of oral complications caused by cancer treatment. Methods: (i & ii) Systematic reviews of randomised controlled trials, using Cochrane methodology were carried out to assess the effects of interventions (oral cryotherapy and cytokines and growth factors for (i)); (iii) Guidelines published from 2005 onwards were appraised using the AGREE II instrument. The guidelines were also assessed to determine whether or not their recommendations were supported by high quality systematic reviews. Results: (i) Both oral cryotherapy and keratinocyte growth factor were found to prevent oral mucositis in patients receiving certain types of treatment. They also appeared to be relatively safe interventions; (ii) Amifostine was found to be beneficial for preventing dry mouth in the short- to medium-term in patients receiving radiotherapy to the head and neck. However, amifostine is associated with side effects; (iii) The quality of guidelines on the management of oral complications caused by cancer treatment is very poor. They are generally poorly reported, methodologically deficient, and the recommendations are rarely supported by systematic review evidence. Conclusions: More high quality randomised controlled trials are needed of interventions for preventing oral mucositis and salivary gland dysfunction. Clinical guidelines in this field should not be used without a rigorous appraisal incorporating an assessment of the evidence base for their recommendations. Different stakeholders, especially systematic reviewers and guideline developers, need to work together to improve the currently low standard of clinical guidelines.