The aim of the present work was to determine the relative transcript abundance of the oestrogen receptor alpha (ERα) and beta (ERβ) gene in long-term cultures (up to 18 days) of pig granulosa cells (GC) obtained from small (1-2 mm; SF-GC) and large (5-7 mm; LF-GC) follicles. GC were cultured in the presence of 10% foetal calf serum (FCS) and one of the following growth factors: leukaemia inhibitory factor (LIF), basic fibroblast growth factor (bFGF), or stem cell factor (SCF). The relative transcript abundance of the investigated genes was measured by real time PCR (RTPCR). In comparison with the control (medium only), LIF significantly increased (P<0.05-0.01) ERα gene expression in SF-GC after 3, 15 and 18 days of culture and after 12 days in LF-GC. The ERβ mRNA level in SF-GC was significantly decreased (P<0.01) by all of the investigated factors after 3, 6, 9 and 12 days of incubation. In conclusion, expression of both types of oestrogen receptors during prolonged culture of pig GC under different conditions suggests the role of oestrogens acting via their receptors in maintaining survivability of porcine granulosa cells in vitro.