Patients and their care providers are increasingly turning to the internet for information. Being faced with this information of very heterogeneous quality, the physician would do well to be informed about the common internet information sources. We investigated the e-mails of a mailing list (or "support group") serving about 380 brain tumour patients and their care providers. The mails were obtained from an archive and grouped according to their topic. Within 6 months, 3,272 e-mails were distributed to every group member. Alternative treatments were the most frequently discussed topics (15 %). These discussions dealt with serious new strategies as well as dubious drugs and methods. A critical attitude towards "quacks" was common, but not the rule. More than 10 % of the mails dealt with debates about therapeutic strategy and about symptoms. The individual course of the participants' illness was often reported very frankly. Emotional support between members played another great role in the support group. Criticism of physicians was rare compared to recommendations of specific therapists (3 % vs. 4 %) and included lack of empathy or sensibility and poor communication between physicians. The brain tumour mailing list is a communication medium for brain tumour patients and their care providers, which distributes and reproduces information of heterogeneous quality. The physician faced with this information should be unbiased but cautious.