Books of correspondence were introduced by Cracow municipal office in 1621. Approximately 90% of the letters are correspondence sent from the city hall. Most of the letters were directed to influential persons, called “patrons”. They were central and province officials, dignitaries of the Church. They were mainly informed about the problems of the city. More than half of the letters were received by clergymen (especially the Bishop of Cracow), castellans, Chancellor of the Crown, provincial governors and the king. The city council also wrote to their relatives. Only 10% of letters were sent to other cities. These were mainly trade related issues. Most of the letters to private persons were not entered into the books. On the other hand registered incoming letters come mostly from the office of the Bishop of Cracow. City of Cracow described in the letters their problems such as tax rates, merchants avoiding to obey the storage law, threats from other armies. City hall referred in the correspondence to their privileges. Most of letters were written in Polish.