Jamestown Canyon virus (JtCV) is an arbovirus and a member of the California serogroup. To our knowledge, all the cases of JtCV have been reported in immunocompetent patients since it was first detected in 1997. We report a case of JtCV encephalitis in a solid organ transplant patient. A 48-year-old woman from Wisconsin had multiple hospital admissions for symptoms of progressive confusion, visual hallucinations, and inability to perform self-care. Initial evaluation was significant for lymphocytes in cerebrospinal fluid (CSF), and multiple infectious and metabolic causes were excluded. Further investigation found JtCV IgM in serum, and CSF. The patient's clinical course was compatible with JtCV encephalitis, and she was treated with ribavirin in addition to reduction of her immunosuppressive medications. She showed gradual and significant improvement in her mental and functional status. JtCV can cause a variety of symptoms that range from a flu-like syndrome to encephalitis. There have been an increased number of reported cases in recent years which is attributed to increased physician awareness and the availability of laboratory testing. Optimal treatment is still not known.