Current serological tests do not reliably diagnose rabies. We describe a technique based on amplification of nucleic-acid sequences to detect rabies-specific RNA in the saliva and cerebrospinal fluid (CSF) of four living patients with rabies. Rabies RNA could be detected in either saliva or CSF, or both, in all patients and as early as day 2 after onset of symptoms. Both saliva and CSF should be serially tested because not every sample can be expected to be positive. The whole process, including automated extraction, isothermal amplification, and detection can be done within 4 h.