Craniopharyngiomas are successfully managed with surgery and / or adjuvant chemoradiotherapy. The transnasal endoscopic route has become increasingly utilised in the management of these challenging tumours. This paper reviews 23 cases from the literature of the rarely reported malignant transformation. Histologically the most common tumour type was a squamous cell carcinoma. Twenty-two percent of the cases were diagnosed as malignant craniopharyngioma at first biopsy. Of the rest the median time from initial benign diagnosis to malignant transformation was 8.5 years (range 3-55 years). The median overall survival after malignant transformation was six months. Malignant craniopharyngiomas are therefore rare and associated with a poor prognosis. Malignant transformation tends to occur years after the initial benign craniopharyngioma diagnosis and is associated with multiple benign craniopharyngioma recurrences. Their analysis shows that contrary to wide spread belief there seems to be a poor colouration between radiotherapy and subsequent malignant transformation.