This study tested the hypothesis that luteal LH receptor (LHr) and follicular LHr and FSH receptor (FSHr) steady-state mRNA levels are greater during superovulation with equine chorionic gonadotrophin (eCG) compared with that with FSH. Heifers were stimulated with eCG (n = 10) or FSH (n = 10), and ovaries were recovered the day before and at 12 and 24 h after luteolysis was induced with prostaglandin F2 alpha (PGF2 alpha). Total RNA was purified from individual follicles and corpora lutea. Steady-state levels of LHr and FSHr mRNA were assessed by slot blot analysis employing homologous cDNA probes. There were no differences in luteal LHr between FSH- and eCG-stimulated animals before luteolysis, and hybridization signals were detected in only one of six animals by 12 h after injection of PGF2 alpha. After PGF2 alpha injection, steady-state levels of follicular LHr were 4-fold lower (P < 0.05) and follicular FSHr mRNA levels were 2.4-fold lower (P < 0.05) in eCG- compared with FSH-treated cattle. In eCG-treated animals, induction of luteolysis led to a significant increase in follicular LHr mRNA levels (P < 0.01) and a significant decrease in follicular FSHr mRNA levels (P < 0.01). There was no such effect of luteolysis in FSH-treated animals. We conclude that superovulation with eCG, compared with FSH, results in lower follicular levels of LHr and FSHr mRNA but does not affect luteal LHr mRNA levels.