Background: Amanita phalloides (Amanita) contains amanitin, inhibiting RNA polymerase II. Partial inhibition with amanitin influences tumor cell-but not normal cell-activity. Patients treated with Amanita often gain a stable disease state without further tumor growth. Aim: Several therapies for prostate cancer are in use so far. This study evaluates the implementation of the Amanita therapy into the therapeutic regimen of today. Methods: 38 Patients with diagnosed prostate cancer were treated with Amanita alone. Prostate specific antigen (PSA) was used as a parameter for tumor cell growth. Data about previous therapies like anti androgen treatment, prostatectomy, chemotherapy or radiation and progression state of the disease were collected, and relationships analyzed. Results: Some patients could be stabilized with Amanita, evidenced by previously increasing PSA that did not increase for at least six months during Amanita therapy. In some patients PSA levels further increased despite Amanita therapy indicating immediate therapy resistance. Analyses revealed that successful Amanita therapy is strongly associated with beginning therapy early, while progressive disease states are often resistant to Amanita (p-value 0,005). Correlation between Study Pre-Protocol