Neurological diseases cause a substantial and increasing personal, social and economic burden. Although there have been exceptions, there is increasing frustration at the limitations of learning from animal models, emphasising the importance of studying human tissue. Neuropathologists work in NHS hospitals examining samples from the brain and related tissues derived from operations (biopsies) or post mortem examinations. Their job is to identify abnormalities, make a diagnosis and try to understand how the abnormalities arise. Neuropathology has existed as a specialty in the UK for 40-50 years and, as a consequence of this work, substantial archives of diagnostically verified tissue have been established nationwide. These archives contain a wealth of tissue from a great variety of neurological conditions, including common conditions such as stroke, head injury, tumours, infections, psychiatric disorders, developmental disorders and many rare conditions, and represent an underutilised resource for research. BRAIN UK (the UK BRain Archive Information Network) networks the tissue archives of neuropathology departments based in 26 regional NHS Clinical Neuroscience Centres to form a virtual brain bank, acting as a "matchmaker" linking researchers needing tissue to the appropriate samples. Through BRAIN UK researchers can gain access to >400,000 samples from a wide range of diseases affecting the brain, spinal cord, nerve, muscle and eye. BRAIN UK has ethical approval which covers the majority of projects, saving the researchers considerable time as they would otherwise have to obtain this approval independently. Over the past 4 years BRAIN UK has supported 48 research projects in many centres around the UK and overseas. In the coming 4 years we want to continue to provide tissue to researchers from existing resources and add newly obtained samples of which >16,000 are becoming available each year. We also aim to gather the results of researchers' studies performed on tissue obtained through BRAIN UK to form a central register of findings which will benefit new researchers wanting to perform new studies on these tissue samples. Finally, we will link BRAIN UK with UK Biobank, which has 500,000 intensively studied participants from the general population, in order to learn more about the origins of neurological disease. As far as we are aware, the BRAIN UK network is unique in the world and is very economical as it makes use of tissue samples already being stored in NHS archives which would otherwise be unused and unavailable to researchers.