The algorithm for three-dimensional SPECT (Single Photon Emission Computed Tomography) diagnostics is developed. A step of the SPECT method is a reconstruction of a spatial local emission coefficients distribution inside a patient body. A tissue absorption correction results in the more complicated problem comparing with traditional X-ray or NMR tomography. The suggested algorithm allows the reconstruction of an unknown emission distribution when an absorption being supposed as an arbitrary function of spatial coordinates is known.