The aim of the study was a comparison of oestrogen secretion from the granulosa cells isolated from porcine ovarian follicles and follicular cysts in the control conditions and under the influence of PMSG (pregnant mare serum gonadotropin). The ovaries were isolated from the 5–6 years old sows, weighting on an average 283.5 ±21.7 kg, in the slaughterhouse. The granulosa cells were isolated from 6–7 mm in diameter ovarian follicles and 9–10 mm in diameter follicular cysts, and after that cultured in DMEM/F 12 (1:1) medium without gonadotropins or with 0.1, 1, 10 and 100 IU/l of PMSG, respectively. After 24 h of culture the media were collected to analyse the concentration of oestrogens (17ß-oestradiol – E-2, oestrone – E-1) by high-pressure liquid chromatography (HPLC, Beckman 125 SM) method with UV detection. In the control conditions, significantly (P ≤ 0.05) lower secretion of steroid hormones from the cystic cells was found (E-2: 2,44 ±0.45 pg, E-1: 2,46 ±0.23 pg / 5´105 cells/24 h) in comparison to the cells from follicles (E-2: 9,8 ±0.93 pg, E-1: 9,24 ±1.15 pg /5´105 cells/ 24 h). The introduction of PMSG to the culture medium, both in the case of granulosa cells from follicles and cysts resulted in significant (P ≤ 0.05) increase in oestrogen secretion. This augmentation was in positive correlation with PMSG doses. After the 24 h period of follicle-derived granulosa cells culture with the highest dose of PMSG (100 IU) 3.9-fold increase in the quantity of secreted E-2 and 3.8-fold increase of E-1 in comparison to control was found. At the same conditions the secretion of E-2 and E-1 from cyst cells was 8.9 and 6.7-fold higher than in control. Apart from the lower quantity of steroid hormones secretedfrom the granulosa cells isolated from cysts in control conditions, their response to PMSG was significantly higher in comparison to the cells isolated from ovarian follicles.