The aim of this study was to examine the effect of diets with different levels of phytoestrogens on testicular changes of oestrogen receptor (ER) α and β mRNA expression in Biłgoraj ganders during three different phases of reproductive activity. Birds were fed diets with low phytoestrogens levels (15.40-40.44 μg/g of total phytoestrogens) based on grass meal (control), or diets with higher levels of phytoestrogens (118.54-151.19 μg/g of total phytoestrogens) based on lucerne meal and soyabean meal. Testes were dissected from animals at the peak of reproductive activity (March), during the descending of reproductive activity (May) and at the beginning of photorefractoriness period (July). The expression of the ERα and β mRNA in testis was examined by semiquantitative RT-PCR. There were not differences in testicular expression of ERα mRNA between ganders fed both diets in March and May. An increasing of this expression in group fed diets with higher phytoestrogens levels in July in comparison to control group as well as to both groups in March and May was observed (281% as well as 441 and 446%, and 830 and 1388%, respectively). The testicular expression of ERβ mRNA between ganders fed both diets during all the experiment time was not significantly different. The greater ERβ mRNA expression in testis from ganders fed diets with higher phytoestrogens levels diets in July than from males fed both diets in March and May (153 and 197%, and 380 and 298%, respectively), and the increasing of this expression in control birds from July in comparison to animals from May (231 and 175%, respectively) were noted.