The goal of the present paper is to study the existence of solutions of the semilinear elliptic system \[ \begin{gathered} -\Delta u+ u= |v|^{q-1} v+ g(x,v)\quad\text{in }\mathbb{R}^n,\\ -\Delta v+ v= |u|^{p-1} u+ f(x,u)\quad\text{in }\mathbb{R}^N,\\ u(x)\to 0\text{ and }v(x)\to 0\quad \text{as }|x|\to \infty,\end{gathered}\tag{1} \] where \({1\over p+1}+ {1\over q+1}= {N-2\over N}\), \(p,q> 1\), which is known as the critical hyperbola. The author proves an existence result for (1).