['The possibility that a specific cytokine profile could be detected in the ovaries of patients with polycystic ovarian syndrome (PCOS) was investigated.', 'Enzyme-linked immunosorbent assay (ELISA) or bioassays were used to assess the concentrations of leukaemia inhibitory factor (LIF), tumour necrosis factor, interleukin 11, gamma interferon, progesterone and oestradiol in follicular fluids from preovulatory follicles collected after ovarian stimulation from 15 PCOS patients, 15 infertile control patients with regular cycles, and 8 oocyte donors.', 'LIF and progesterone concentrations were significantly lower in the follicular fluid of PCOS patients (LIF median: 265 pg/ml) compared with controls (LIF median: 816 pg/ml); LIF and progesterone follicular fluid concentrations were correlated (r = 0.720, P = 0.0001). The LH/FSH ratio was negatively correlated with LIF concentrations (r = - 0.714, P = 0.0075). Although the PCOS and control patients did not differ significantly in age, ovarian reserve or IVF indication, the implantation rate was significantly lower among the women with PCOS (IR = 9 versus 21%, P = < 0.01).'] Is follicular fluid concentration of leukaemia inhibitory factor decreased among women with polycystic ovarian syndrome during assisted reproduction cycles?