Expectations concerning key economic variables certainly influence decisions undertaken by economic agents. Since assumption of rationality forms the basis of neoclassical economic theory, question of whether expectations of industrial enterprises are indeed formed rationally deserves careful attention. In this paper, we analyze two basic properties of expectations rational in sense introduced by J. F. Muth – that is, unbiasedness and orthogonality – taking into account issue of non-response and weighting schemes. We find that rationality of expectations of Polish industrial firms is not sensitive to these factors. Independently from non-response and weighting issues, expectations concerning relative changes in production remain unbiased but not efficient with respect to freely available information.