<p>Background: The purpose of the study was to assess whether the coadministration of 150 <em>IU</em> of recombinant LH instead of 75 <em>IU</em> in women aged 35-39 improves the results in agonist ICSI cycles stimulated with 300 <em>IU</em> of recombinant FSH.<br /> Methods: In this study, two ovarian stimulation protocols coexisted which were identical except in the administered dose of recombinant LH, for which some patients received 150 <em>IU</em> (n=231) and some received 75 <em>IU</em> (n=216). Both groups received 300 <em>IU</em> of recombinant FSH. There were no differences in the demographic characteristics of both groups. Gonadotropins were reimbursed by the National Health System. Statistical analysis was performed by Student&rsquo;s t test, &chi;2, and ANCOVA. Significance level was established at p=0.05.<br /> Results: The number of retrieved oocytes was slightly higher in the 300/150 group (9.06&plusmn;5.53 vs. 8.61&plusmn;5.11), but the differences were not significant. Results were similar with the number of metaphase II oocytes (7.18&plusmn;4.86 vs. 6.72&plusmn;4.72) and the number of fertilized oocytes (4.64&plusmn;3.2 <em>vs.</em> 4.23&plusmn;2.72). The per-transfer clinical pregnancy rates exhibited close similarity between both groups (32.84% vs. 32.46%), as did the per-transfer live birth rates (29.90% vs. 30.37%) and the implantation rate. The rate of hyperstimulation syndrome (OHSS) as well as the rate of cancellation due to OHHS risk was similar in both groups. There was also no difference in the miscarriage rate. When results were expressed by per started cycle or by oocyte pick- up, the results remained very similar in both groups.<br /> Conclusion: In women aged 35-39 undergoing ovarian stimulation with recombinant FSH in agonist cycles, the coadministration of 75 or 150 UI of recombinant LH did not influence pregnancy rates. However, a slight increase in the number of retrieved oocytes should not be disregarded.</p>