The title of this thesis is the “CONVERSION OF LETER C IN ESTABLISHING LEGAL CERTAINTY IN KLATEN REGENCY ”. The problem, has the conversion of Leter C in the Klaten Regency established the rule of law? The purpose of this study to determine, assess, and analyze whether the conversion of Leter C has established do not the legal certainty in Klaten Regency. Type of this research is empirical legal research which means a study that focuses on the behaviour of the legal community. The sources of data consist of primary data as the main data and secondary data. The conversion of Leter C in the Klaten Regency has established the legal certainty and it is accordance with Government Regulation Number 24 Year 1997 on Land Registration and PMNA / KBPN Number 3 of 1997 on the Implementation of Government Regulation Number 24 Year 1997.