Under the Turkish Code of Obligations, “Gambling and Betting” debts are regulated as “non-suitable and non-prosecutable”. In this respect, gambling and betting debts are determined as “incomplete debts – obligatio naturalis” in the sense of Turkish law of obligations. According to Article 27 of the Turkish Code of Obligations: “Contracts that are contrary to the mandatory provisions of the law, morality, public order, personal rights or whose subject matter is impossible are absolutely null and void”. The main source of the Turkish Code of Obligations is the Swiss Code of Obligations. The Swiss Code of Obligations contains almost the same provisions. However, Turkish and Swiss law does not only consist of the Code of Obligations. This is where the main point of our study differs. Because, although gambling and betting debts are defined as incomplete debts in the Turkish Code of Obligations, “gambling (casinos)” is considered as “crime” and prohibited in the Turkish Criminal Code. However, according to the Turkish Misdemeanor Law, “gambling” is prohibited and sanctioned as a “misdemeanor”. Many other provisions also contain prohibitive provisions on gambling and betting. First of all, the Turkish Code of Obligations itself, in Article 27, recognizes contracts that are contrary to “mandatory provisions” and “morality” as “null and void”. Gambling provisions prohibited by “mandatory provisions” in Turkish public law directly affect Turkish private law. For this reason, with this article, it has been criticized that an act prohibited in public law is defined as “incomplete debt” in the Turkish Code of Obligations. Although there are different opinions, it can be said that gambling is generally “immoral” according to the Turkish social structure and the provisions of the legislation. Immoral contracts are also “null and void” according to Article 27 of the Turkish Code of Obligations. In the content of the Turkish study, this contradiction in Turkish law is expressed with many other reasons and it is stated that legal regulations should be made to eliminate these contradictions. In contrast, Swiss law does not criminalize “gambling”. In fact, casinos are legally regulated and protected under Swiss law. Furthermore, in Swiss law, casinos are regulated in detail by a special law, the Swiss Federal Gambling Act. One of the most important details of this law is that a large part of the revenues to be obtained as a result of the regulation of casinos will be transferred directly back to the public in accordance with the provisions of the social state principle. In addition to these regulations in Swiss public law, unlike Turkish law, an “additional provision” has been added to the Swiss Code of Obligations. By adding Article 515a to the Swiss Code of Obligations, casinos are also regulated under private law, thus ensuring “harmonization” between different branches of law. As can be seen, when Turkish law is compared with Swiss law, the contradiction in Turkish law will be clearly seen. Within the Swiss legal system, there is a harmonization and updating with all branches of law. On the other hand, despite the provisions regarding gambling, which is considered a “crime” in Turkish criminal law, similar situations are accepted as “incomplete debt” in the Turkish Code of Obligations. It is normal to have the same provision in Swiss law. Because in Swiss law, there is no prohibitive provision in the Criminal Law regarding gambling. For this reason, this article is not an analysis of the provisions of the existing Turkish Code of Obligations regarding gambling and betting, but rather a criticism of these provisions. In other words, in this respect, this study criticizes the “de lege lata / law as it is” and discusses the “de lege ferenda / law that should be”. For this reason, it is suggested to the legislator to “harmonize” the legal system rather than a suggestion to allow or disallow gambling. Following this recommendation, if the legislator regulates gambling and casinos and makes the necessary legal arrangements, the contradictions within the Turkish legal system will be eliminated. On the other hand, if there is a decision to keep the current prohibitive regulations, we believe that the provisions regarding gambling and betting in the Turkish Code of Obligations and related legislation should be amended and subjected to the sanction of “final nullity”. Since there are few articles written critically on this subject in Turkish law, of course, we have not been able to address every issue, but only the issues that we think should be discussed with the main headings and we have tried to provide direct access to the relevant sources instead of general sources.