A total of 48 patients with head and neck cancer were studied. All patients were treated with radiotherapy, chemotherapy and surgery was added in some of the cases. Patients were randomized into control and the treatment arms. Three oral swabs for candidiasis was taken from all the patients, first one was taken before start of radiotherapy, second one during third week of treatment and last swab was collected at the end of treatment. Patients in the treatment arm were given prophylactic flucanozle 50 mg oral daily during the radiation treatment. The main end points of the study was to evaluate the effect of fluconazole on prevention of oral candidiasis and to determine whether fluconazole prophylaxis will reduce the severity of oral mucositis. Patients were assessed for mucositis weekly. Patients in the treatment arm had less incidence of oral candidiasis and less severe mucositis as compared to the control arm. Prophylactic use of oral flucanazole is effective in reducing the incidence of oral candidasis and also the severity of oral mucositis.