A joint stock company is a company characterized by the share capital of the company divided into shares. Each company acts in order to achieve the set goals defined by the founders of the company on the basis of prescribed acts, which is the legal framework for the management of the company and the conduct of business. The General Assembly of a joint stock company represents the Assembly of all shareholders. The shareholders of the company exercise their rights at the general assembly. The General Assembly of a joint stock company is the only body in whose work all shareholders of the company can actively participate, even those members of the company who do not have the right to vote. At the general assembly, the shareholders express their will, the will of the company is formed, which is its main role. Depending on the decisions of the General Assembly, they can be positive or negative, depending on the outcome of the vote. Observing the substantive and formal rules of law, the decisions of the General Assembly are divided into: apparent decisions, decisions without legal effect, null and void decisions. When we talk about null and void decisions, we are talking about decisions that have such shortcomings and are considered not to have been made, or not to exist. The general law stipulates that shortcomings of decisions are stated if the decision is contrary to the Constitution of the Republic of Croatia, the morals of society and coercive regulations. The nullity of a decision arises from its very adoption on the basis of law. Therefore, such a decision cannot have legal effect and is treated as if it never existed. The nullity of the decisions of the General Assembly shall be declared by the court, on the basis of a lawsuit for establishing nullity or a lawsuit challenging such a decision. Defining decisions are defined as decisions that are contrary to the social contract, statute or law. In such a decision, the existence of grounds for rebuttal does not affect its validity and as such will produce legal effects until someone successfully rebutts it. A conciliatory decision "hangs in the air" until the possibility of refutation is eliminated, in which case it will be valid, or until someone refutes it, and thus it will become null and void. The aim of this paper is to explain in detail the notions of nullity and rebuttal of the decisions of the general meeting of the joint stock company, while analyzing and stating the reasons that lead to this. At the same time, the paper will study and explain the processes of emphasizing the nullity and rebuttability of the decisions of the General Assembly, the manner of their removal and the impact on the joint stock company.