Objective: Relevancy of the reference genes have not been investigated in crayfish tissue samples. Various genes have been proposed for establishing a reference level to analyze qPCR results obtained in different tissue samples. However, majority of those genes have been investigated solely in mammalian species. There is no report related to the relevancy and the efficiency of those common reference genes in crayfish tissue samples yet. The primary aim of the present work is to compare the expression level of a set of reference genes in various crayfish tissue samples to establish a reliable reference gene for quantitative expression level comparisons.