(11)C-methionine (MET) is the most popular amino acid tracer used in PET imaging of brain tumours. Because of its characteristics, MET PET provides a high detection rate of brain tumours and good lesion delineation. This review focuses on the role of MET PET in imaging cerebral gliomas. The Introduction provides a clinical overview of what is important in primary brain tumours, recurrent brain tumours and brain metastases. The indications for radiotherapy and the results and problems arising after chemoradiotherapy in relation to imaging (pseudoprogression or radionecrosis) are discussed. The working mechanism, scan interpretation and quantification possibilities of MET PET are then explained. A literature overview is given of the role of MET PET in primary gliomas (diagnostic accuracy, grading, prognosis, assessment of tumour extent, biopsy and radiotherapy planning), in brain metastases, and in the differentiation between tumour recurrence and radiation necrosis. Finally, MET PET is compared to other nuclear imaging possibilities in brain tumour imaging.