Abstract. In the work we consider some inverse problems relatively domain for the Laplace operator. The aim of the work is to find a domain under the condition that, the function, expressed by spectral data of the problem is given in the boundary of this domain. Introduction. Solution of a wide class of practical problems is reduced to the minimization of the functionals related with eigenvalues [1]. The study of shape optimization problems for the eigenvalues of an elliptic operator is a fascinating field that has strong relations with several applications as for instance the stability of vibrating bodies, the propagation of waves in composite media, the thermic insulation of conductors. Investigation of such problems is important also for study of the qualitative properties of the eigenvalues [2]. In the work we consider some inverse problems relatively domain. In its mathematical formulation the problem consists in taking an elliptic operator and considering its eigenvalues λ k as a functionals of the domain D where the problem is solved. In the work these problems are reduced to the minimization of the functionals including spectral data of the corresponding operators. Usually in such problems obtained optimality conditions for domain involve eigenfunctions that makes difficult their use in the determination of the domain. Here we reduce the considering shape optimization problems to variational formulation, get some optimality conditions and a formula for the eigenvalue corresponding to the optimal domain. Note that the obtained formulas don't include an eigenfunction. It makes them interesting both from practical and theoretical points of view. For the sake of simplicity we consider only Laplace operator, but the results may be extended for other elliptic operators.