OBJECTIVE To study the expression of mRNA for Kit ligand 1 (KL1), KL2, FSH receptor (FSHR), pregnancy-associated plasma protein (PAPP) and P450 in granulosa-lutein cells from IVF patients and its relationship with the infertility diagnosis and IVF outcome. DESIGN In vitro assays. SETTING University laboratory and private IVF center. PATIENT(S) A total of 113 women undergoing IVF. INTERVENTION(S) Quantitative reverse-transcription polymerase chain reaction in granulosa-lutein cells from pooled follicles. MAIN OUTCOME MEASURE(S) Expression of mRNA for KL1, KL2, FSHR, PAPP and P450 in infertility patients with different infertility diagnoses. RESULT(S) Infertile patients with healthy ovaries show positive correlations among KL1, KL2, FSHR, PAPP, and P450 gene expression levels. In patients with ovarian disease, the correlation between KL1 and KL2 gene expression is maintained, but correlations between KL1/KL2 and FSHR, PAPP and P450 are not present except for KL1/FSHR in endometriosis and KL2/P450 in polycystic ovary syndrome. FSHR/KL1 and FSHR/KL2 expression correlates positively only in women who became pregnant. CONCLUSION(S) Findings in healthy human ovaries agree with the feedback model of bone morphogenetic protein 15-KL1/KL2 cross-talk between oocyte and granulosa cells described in other species. The complex relationship between the expression of these genes seems to be disrupted in patients with infertility of ovarian origin. A normal pattern of gene expression and feedback seems to be associated with pregnancy.