Acute appendicitis due to metastasis of prostatic carcinoma is very rare, and only five cases of metastasis of prostatic carcinoma are described in the literature. We report the case of a 73-year-old man with a history of an adenocarcinoma of the prostate with multiple bone metastases. The patient was admitted to the emergency department with symptoms and signs of an acute appendicitis which was confirmed by computed tomography (CT). Laparoscopic surgical exploration was performed, affirming an acute appendicitis with a suspicious lesion in the appendix base. Due to the location of the lesion, an ileocecectomy was performed. Histopathological and immunohistochemical examinations of the specimen showed an extrinsic infiltration of the appendix by adenocarcinoma metastasis expressing the prostate-specific antigen (PSA). These results confirmed an acute appendicitis caused by metastasis of prostatic adenocarcinoma.