The most common disease ofappendix is acute appendicitis. There have been at least 20 case reports of metastasis-induced appendicitis in English literature. The authors reported a 62-year-old Thai man who underwent appendectomy due to classical symptoms and signs of acute appendicitis and was subsequently referred to Siriraj Hospital for proper management after a pathological report of metastatic adenocarcinoma to the appendix. By morphology, the primary site was thought to be the prostate gland. Confirmation was done based on serum PSA study, transrectal ultrasound-guided core needle biopsy, and review of the material from Hua Hin Hospital. Orchidectomy was performed with satisfactory outcome. The patient was doing well for two years before upper gastrointestinal hemorrhage and obstructive jaundice caused by another aggressive tumor developed. He died of the second tumor associated with subsequent renal failure in spite of good response to orchidectomy.