Before contemplating surgery for cerebrospinal fluid (CSF) rhinorrhoea it is vital that the correct diagnosis is established. This can be done using immunofixation of beta-2-transferrin, that is nearly always positive in cases of CSF rhinorrhoea. Fluorescein lumbar puncture is useful in establishing the exact site of a leak and also in confirming the absence of a leak where the clinical suspicion is high but the beta-2-transferrin is negative. High resolution computed tomography (CT) scanning is a useful radiological investigation for identifying a bony defect. We present nine patients who presented with clear rhinorrhoea that was clinically highly suggestive of a CSF leak. Three of these patients had undergone previous craniotomies for presumed CSF rhinorrhoea. The diagnosis of CSF rhinorrhoea was excluded in all patients using beta-2-transferrin with or without fluorescein lumbar puncture. The authors believe that measurement of beta-2-transferrin should be mandatory before surgery for CSF rhinorrhoea.