The aim of this study was to examine the effect of A-trichothecenes T-2 and HT-2 toxins combined with insulin-like growth factor I (IGF-I) on the release of steroid hormone progesterone (P4) by porcine ovarian granulosa cells (GCs). The cells were incubated without (control) or with treatments of A-trichothecenes T-2 (100 and 1000 ng/mL)/ HT-2 (100 and 1000 ng/mL) combined with IGF-I (1, 10 and 100 ng/mL) for 24 h. Progesterone secretion was determined by RIA. The release of P4 by GCs after addition of T-2 toxin (at 100 ng/mL) combined with IGF-I (at 10 but not at 1 and 100 ng/mL) and HT-2 toxin (at 100 ng/mL) combined with IGF-I (at all doses) was significantly (P < 0.05) inhibited. On the other hand the release of P4 after addition of T-2/ HT-2 toxin (at 1000 ng/mL) combined with IGF-I (at all doses) was significantly (P < 0.05) stimulated. Alone IGF-I addition (at 10, 100 but not at 1 ng/mL) significantly (P < 0.05) stimulated P4 release by GCs. The results of our in vitro study indicate the T-2 and HT-2 toxins combined with IGF-I could modify progesterone secretion by porcine ovarian granulosa cells and potentially regulate process of steroidogenesis in the ovaries. Currently, occurrence of mycotoxins in food and feed is a worldwide problem and therefore study of these toxins as well as their interaction with different substances such as growth factors could be beneficial for better understanding of mechanism of their toxic effects in organism.