Bleomycin has been used in the treatment of brain tumors for over 30 years. Currently, we are evaluating electrochemotherapy (the use of electric pulses to enhance uptake of bleomycin) for patients with secondary brain tumors. We, therefore, reviewed the literature with specific reference to the tolerability and toxicity of bleomycin. Using the keywords 'brain' and 'bleomycin', a database search without date restriction was performed and over 500 articles were found. Twenty-five articles were used for this study based on relevance determined by: (i) clinical studies, (ii) use of bleomycin, and (iii) direct injection into brain tissue or cysts. There were two main indications for the use of bleomycin directly into the brain: (i) cystic tumors in the form of craniopharyngiomas and (ii) solid brain tumors such as glioblastomas and astrocytomas. The most frequent adverse effects reported were transient fever, headaches, nausea and vomiting, lethargy, and peritumoral edema. Out of 189 patients treated from 1973 to 2007, only five patients (3%) had severe and six patients (3%) had moderate adverse effects. One death was directly related to this treatment, where very high doses were used. Two patients developed loss of vision and two patients had hearing loss because of the treatment. All cases with severe and moderate adverse effects except one were patients with craniopharyngiomas and probably because of tumor localization in the deep brain. In conclusion, bleomycin injection into the brain has been fairly well tolerated at doses much higher than that used in electrochemotherapy.