[en] The influence of stacking disorder on the optical properties of layered GaSe crystals is discussed. X-ray analysis show that GaSe crystals grown with Bridgman method consist of a mixture of two modification (beta, delta). In sample of delta modification part, anomalous refraction by one of various lights is observed (He-Ne, Dye, YAG:Nd⁺³ lasers and collimated beam). The incident light is perpendicular to the surface of the sample; contrary to passing always along the incoming direction, it splits to two parts making angles of 13^o and 70^o. In transmission and photoconductivity spectra of the beta-modification, free exciton absorption exists, whereas this peak is absent in these spectra in delta-modification part samples. The result of the measurements on GaSe indicates that the mentioned properties are explained by stacking disorder of the layers. (Authors)