Introduction. Delusional infestation is a rare monosymptomatic hypochondriacal psychosis according to The Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013). It can be a primary disorder or associated with an underlying psychological or physical disorder. It commonly presents as delusional parasitosis, and less than 1% may be fungi related. We present this case as it is a rare presentation of a rare condition. Case Presentation. Our patient is a 60-year-old Caucasian man who presented with a 7-year history of delusional infestation manifested as a disseminated fungal infection. He had previously been reviewed by multiple physicians for the same with no systemic illness diagnosed. After multiple reviews and thorough investigation we diagnosed him with a likely delusional disorder. As is common with this patient cohort he refused psychiatric review or antipsychotic medication. Conclusion. A delusion of a disseminated fungal infestation is a rare condition. It is exceedingly difficult to treat as these patients often refuse to believe the investigation results and diagnosis. Furthermore, they either refuse or are noncompliant with treatment. Multidisciplinary outpatient evaluation may be the best way to allay patient fears and improve treatment compliance.