Medical diagnostic criteria for Munchausen Syndrome by Proxy are presented. The strength of the known facts may vary from case to case, and thus there may be different degrees of diagnostic conviction. Therefore, diagnostic criteria for a definitive diagnosis, and a possible diagnosis of Munchausen Syndrome by Proxy are provided. Because the gathering of evidence in a case may, ultimately, diminish or exclude the diagnosis of Munchausen Syndrome by Proxy, diagnostic criteria for the inconclusive determination and the definitely excluded diagnosis are also enunciated.