OBJECTIVE To compare double homologous versus only one intrauterine insemination (IUI) by stimulated cycle. METHODS In a prospective, comparative study 138 patients were included, who underwent to intrauterine insemination; not inclusion parameters were: patients with cancelled cycles by poor response or by ovarian hyperestimulation syndrome risk. Patients were divided in two groups: Group 1 (N = 69) one insemination at 36 hours after human gonadotrophin chorionic hormone (hCG) and group 2 (N = 69) two inseminations 24 and 48 hours after hCG. Sperm separation was done with swim up, wash and resuspended or isolate techiques, and ovarian stimulation was done with recombinant FSH, menotrophins or clomiphene citrate. Statistical analysis was made by T Student and chi2 tests. RESULTS The overall pregnancy rate was 13.04% per cycle; and seminal characteristics after seminal preparation were similar. We observed better pregnancy rates in the patients with ovulatory dysfunction and endometriosis (14.9% and 18.2%). No differences were established in pregnancy rates when patients were compared in function to seminal preparation. CONCLUSIONS Double IUI at 24 and 48 hours after hCG has the same results in pregnancy rates than only one IUI correctly indicated 36 hours after hCG, but the costs increases in double insemination.