Dietary fatty acids (FA) have an effect on animal reproduction. The purpose of the study was to find out how supplemental flaxseed can modulate the FA metabolism and how FA can influence the release of ovarian hormones and functions of the uteri through the modulation of their specific receptors. Cycling mice were fed a basal diet (control) and basal diet fortified with 10% flaxseed for 6 weeks to examine its influence on the structure and function of the ovaries and uteri, and serum levels of FA. Unlike controls (30%), 100% of mice fed flaxseed exposed oestrus at the end of the supplemental period. Serum FA were analysed using gas chromatography. The ovaries and uteri underwent histological and immunohistochemical analyses, respectively. The ovarian fragments were cultured with or without follicle-stimulating hormone and culture media were analysed for progesterone (P4) and oestradiol-17β (E2) using immunoassays. Dietary flaxseed increased the serum FA concentration, sizes of the ovaries and primary follicles, the release of P4 and E2, the thickness of endometrium and myometrium, and altered the expression of oestrogen and progesterone receptors in all uterine compartments. Dietary flaxseed can promote ovarian steroidogenesis and uterine activity in the mouse.