This study examines and investigates based on analysis and research the surety against occult defects of a sold unit. As a primarily step toward a clear understanding of the subject being investigated, the term defect is defined, and the legal basis of the surety against occult defects is comprehensively explained. The first chapter of the study presents an answer to the far reaching question concerning the terms and conditions on which surety against occult defects can be applied, as it is recognized that not all defects require surety. The answer is given through an examination of the extent to which a defect may affect a sold unit, and how old and occult the defect may be. The examination also considers the buyer's ignorance of the defect, and the purchased unit being a non-auction item sold by a legal body. While the second chapter of the study deals with the provisions of the surety case through an exploration of the case parties, the extent to which the surety against occult defects is related to the general system, prescription and obsoleteness of the surety case, and the difference between the surety against occult defects and the defects of consent. The third chapter spotlights on the rights and obligations of the buyer and the seller through an investigation of the necessary procedures to be taken as a primarily step toward a surety case. In addition, emphasis is put on the buyer's rights when conditions are met, as well as on the obligations of both the buyer and the seller in case the sold unit is returned. Surety provisions in emergencies are also examined. Finally, the study is concluded with the most important findings and recommendations