The article is dedicated to such unknown artifact of the Russian historiography as the Chronicle of I. Lavrovsky. This monument dated by the end of the XV century was kept in the collection of the Peremyshl reader of canons I.A. Lavrovsky. The authors considered the question about the discovering of the chronicle. It is considered that the artifact was introduced into the science in the soviet period. But the slavists knew about the chronicle from the first part of the XIX century. Firstly, the mentionings about the artifact were considered in the article. P.I. Keppen was the first researcher who wrote about the chronicle. He located it in the Galicia in January, 1822 and studied the local manuscript collections. The attention of P.I. Keppen was attracted by the Russian chronicle from the collection of I. Lawrovsky. The researcher mentioned this manuscript in his notes. Other slavists knew about this artifacttoo (J.F. Holovatsky, D.I. Zubritsky, A. Belovsky). Moreover, the owner of the chronicle connected with participants of the society of the count N.P. Rumiantsev. Secondly, the authors investigated the question about the search of the original, wich was lost. The last mentioning about the manuscript of the XVI century dated by the 1840 (J. F. Holovatsky). The artifact was lost after the death of Lavrovsky. A. Belovsky was looking for this manuscript, but he managed only the copy of the chronicle. Thirdly, the authors reported about the copies of the chronicle. We know four copies of artifact dated by the 20-30 years of the XIX century in the Lavrovsky's environment (LNNB, Ossol. 2126; Bavor. 526; coll. National house № 217; Ossol. 2178). The big quantity of the copies testify about the interest to the chronicle between the slavists of the XIX century. I. Lavrovsky connected with N.P. Rumiantsev about the creation of the monument's copy, but this copy was not found in the materials of the count. May be any of these four manuscripts could be intended to the Rumiantsev. In conclusion, the authors could investigate the process of the introduction of the chronicle in the science. The slavists of the XIX century negotiated about the creation of the chronicle's copies. Subsequently the original was lost. The attitudes of A. Belovsky to find this manuscripts did not succeed. The following researchers worked with these copies. In the end of the XIX century the chronicle was forgotten. The second opening of the chronicle was done by V.I. Buganov.