The management of patients with suspected viral encephalitis has been revolutionised in recent years with improved imaging and viral diagnostics, better antiviral and immunomodulatory therapies, and enhanced neurointensive care. Despite this, disasters in patient management are sadly not uncommon. While some patients are attacked with all known antimicrobials with little thought to investigation of the cause of their illness, for others there are prolonged and inappropriate delays before treatment is started. Although viral encephalitis is relatively rare, patients with suspected central nervous system (CNS) infections, who might have viral encephalitis, are not. In addition, the increasing number of immunocompromised patients who may have viral CNS infections, plus the spread of encephalitis caused by arthropod-borne viruses, present new challenges to clinicians. This article discusses the Liverpool approach to the investigation and treatment of adults with suspected viral encephalitis, and introduces the Liverpool algorithm for investigation and treatment of immunocompetent adults with suspected viral encephalitis (available at www.liv.ac.uk/braininfections).