Capgras Syndrome is a rare delusional misidentification syndrome where the patient thinks that someone, to whom he/she has strong emotional attachments, has been substituted by a "fake" person who looks identically the same. The exact roots of CS have not been elucidated; however, organic etiologies such as, B12 deficiency and structural abnormalities were identified. Because CS is usually observed in the presence of a psychiatric disorder, it is difficult to isolate and analyze the underlying organic etiologies. From this perspective, we present a CS case with a diagnosis of delusional disorder and an underlying B 12 deficiency who showed significant clinical improvement with B12 replacement and 30 mg per day aripiprazole therapy. Based on our findings, it can be suggested that B 12 levels should routinely be checked in CS patients and taking different etiologies into consideration and including them within the treatment plan can increase clinical success.