This study is designed to compare the efficacy of a novel stimulation protocol with the conventional low dose step-up and step down regimens in older than 30 years PCOS patients undergoing in vitro fertilisation. The novel regime was proposed under the basis of the combined effectiveness of the two standard protocols to induce a uniform follicular growth and forms a continuation to the author's previously published results examining a similar approach in younger PCOS candidates. In total 225 patients have been recruited for this study. The stimulation protocol will be assigned under the basis of prospective randomization using sealed and numbered envelopes. All patients will be down regulated using a desensitisation agent administered on day 2 of spontaneous or induced withdrawal bleeding. The initial dosage in the low dose step-up regimen (group A) will be 150 IU/d of FSH for the first 6 days followed by an increase of 75 IU thereafter. In the step-down regimen (group B) patients will administer a starting dose of 300 IU/d of FSH for the first 3 days followed by a decrease to 225 IU/d for the next 3 days. This dosage will be further decreased to 150 IU/d or sustained at 225 IU (according to the initial response) until the day of the hCG injection. Group C, patients received 225 IU on day 1 followed by a decrease to 150 IU on day 2. On day 3 the dosage will be increased back to 225 IU. This alternation of injection dosage will be followed until day 6. According to the initial ovarian response the dosage will be sustained at 225 IU/d or 150 IU/d until the day of the hCG injection. The 10,000 IU hCG will be administered when at least two follicles had reached a mean diameter of 18 mm and the serum E2 levels were consistent with the ultrasound findings. Egg retrieval will be undertaken at 35 hours after the administration of the hCG injection. Oocytes recovered will be inseminated 4 hours post egg collection. Patients will receive 3 embryos on the third day of development. The luteal phase will be supported by progesterone suppositories starting on the day of the egg collection. A positive outcome will be detected by a serum β-hCG analysis 13 days after embryo replacement. The presence of a fetal heart pulse on ultrasound 3 weeks later confirmed a clinical pregnancy.