Photodynamic therapy is a new form of cancer treatment which can serve as an adjuvant therapy for malignant glioma. It is based on the selective retention of a photosensitive dye in tumour tissue. Subsequent exposure of the tumour to light of an appropriate wavelength causes selective destruction of tumour tissue. Experimental data indicates that the blood-brain barrier plays an important role in the delivery of the photosensitizer to a brain tumour and that intratumoral injection of the photosensitizer may be advantageous as compared to intravenous administration. A limited group of patients have entered clinical trials. Treatment protocols varied too much and the number of patients was too small to draw any conclusions on the efficiency of PDT of gliomas.