Leniency programs have widely been recognized as implementing a fundamental change in cartel investigations conducted by the antitrust enforcement agencies of major jurisdictions around the world, including the Korea Fair Trade Commission (the “KFTC”). In Korea, however, the KFTC’s leniency program has been criticized as granting immunity to companies that have reaped improper financial gains from cartel activities. In response to this criticism, the KFTC has amended several times applicable law and regulations and relevant guidelines.It is difficult to deny the efficacy of a leniency program, which produces the dual effect of detection with respect to existing cartels and deterrence with respect to future cartels. Under the Korean antitrust regime, the KFTC conducts cartel investigations without the authority to compel submission of documents or testimony of witnesses. For this reason, the KFTC’s leniency program is indispensable to its detection and investigation of cartels, which are by nature secretive.A leniency program must be both predictable and transparent if it is to be effective. That is to say, the legal benefits to be gained from a leniency application, including reduction of any administrative fine, must be ascertainable while it must be clear from the outset that the antitrust enforcement agency will not resort to any arbitrary exercise of its discretionary authority over the course of implementation of the leniency program. By repeatedly amending applicable regulations and guidelines, the KFTC has made efforts to enhance the predictability and transparency of its leniency program. Despite these efforts, however, uncertainties about the leniency program still remain, at least from a potential leniency applicant’s perspective.This article addresses various practical issues faced by a potential leniency applicant in Korea and proposes solutions for resolving these issues. Both the issues and their proposed solutions, however, must be discussed without undermining the efficacy of the leniency program or the indispensable role now played by the leniency program in the KFTC’s cartel enforcement regime. Specifically, this article addresses the following practical issues faced by a potential leniency applicant in Korea: the scope of evidence that must be submitted in a leniency application; joint leniency application; the degree of cooperation that is required to maintain a leniency standing; restrictions on leniency benefits granted to repeat offenders; the KFTC’s duty to maintain confidentiality of a leniency application and applicant; restrictions on leniency benefits granted to the second leniency applicant with respect to a two-party cartel.