Beef tenderloin is a long cylindrical muscle that is found in the loin near the backbone. It is between the sirloin and the top sirloin and stretches forward to the short loin. The tenderloin is easy to carve and very tender. The tenderloin does not have a lot of marbling, but it is flavorful and is considered to be a prize cut of meat. Filet mignon steaksare from the same cut of meat.