The article presents the information of the Bulgarian anonymous chronicle about the death of the sons of Tsar Ivan Alexander – Ivan Assen and Michael Assen. According to this historical source they have died in battle with the Turks. According to the author, Ivan Assen was killed in the 40s of the 14th century. His funeral is presented in Codex Vaticano Slavo 2 (1344/1345). Michael Assen died in 1354 after the capture of Gallipoli by the Ottoman Turks.