Liability for material defects is a current legal and everyday topic. Therefore, the goal of this diploma thesis is to elaborate as much as possible the topic of responsibility for material defects as one of the ways of real strengthening of the obligation-legal relationship, taking into account other ways of strengthening the obligation-legal relationship, and especially the changes that occurred in the institute of responsibility for material defects with the last amendment to the Law on obligations. In order to be able to hold a discussion on the mentioned topic, the work elaborates in detail the institute of the responsibility of the seller for material defects, starting with the cases in which the defects exist, and all through the inspection of things, timely notification to the seller, the buyer's rights, and finally up to the deadlines in which the buyer has his rights can achieve. Cases in which there is no liability for material defects, removal of defects, termination of the contract, as well as the fundamental differences between the institute of guarantee and the institute of liability for material defects are only some of the chapters elaborated in the paper with the aim of explaining the institute of liability for material defects itself. For the sake of easier understanding of the mentioned topic, the work is divided in detail into paragraphs in which each of the constituent parts of the institute of liability for material defects is elaborated in detail. At the end of the work itself, all the key changes that have occurred within the institute of responsibility for material defects are summed up, which are crucial for dealing with the existence of material defects.