Confidentiality is one of the oldest principles of the medical profession that impacts on the relationship between physician and patient, the personal interests of patient and physician and consequently social welfare. While emphasizing the necessity of confidentiality, religious teachings consider disclosure of others' secrets a sin that deserves punishment thereafter. Nowadays, medical developments and the invention of new diagnostic and therapeutic procedures as well as the vastness of the informatics world make disclosure of patients' secrets easier than ever. This review article is the result of a descriptive study, and the information was collected using reliable library and internet resources. It will first expound the concepts and principles of confidentiality in medical ethics as well as Islamic ethics, and will then proceed to a comparative review of the similarities and differences in these two sets of­­­­ ethical views on the issue of confidentiality. In addition to the emphasis of medical ethics and Islamic ethics on the necessity of confidentiality in order to win public trust, both sets of teachings cover two areas of personal and public discretion, while in Islamic ethics, the issue extends to a third from, namely religious confidentiality. This makes Islamic ethics more comprehensive in the sense that based on Islamic teachings, the person who keeps someone's secret will also be rewarded in the Hereafter. Also, in medical ethics, only the behavior of the health staff is evaluated and their moods and motives are not taken into consideration, while Islamic ethics pays attention to human dispositions and therefore confidentiality is more stable and can maintain its efficiency without external supervision.