OBJECTIVE: To perform a highly detailed semen analysis in a man whose wife had a partial mole.DESIGN: Case report.SETTING: Gynecology departments of two university hospitals and a laboratory of histology/embryology.PATIENT(S): A 32-year-old man whose wife had a partial mole.INTERVENTION(S): Sperm characteristics were examined by light microscopy, morphology was analysed by electron microscopy (TEM), DNA fragmentation was evaluated by TUNEL using fluorescence microscopy, and chromosomal abnormalities were assessed by fluorescence in situ hybridization using probes for chromosomes 13, 15, 16, 18, 21, 22, X, and Y.MAIN OUTCOME MEASURE(S): Sperm count, motility, morphology, DNA fragmentation, and incidence of diploidy, tetraploidy, and aneuploidy.RESULT(S): Sperm concentration was 61 million/mL, with 31% progressive motility and 4% normal morphology. TEM revealed a high incidence of head, neck, and tail abnormalities as well as the presence of phagocytes. DNA fragmentation was within normal limits (11.6%). Aneuploidy levels were low for all chromosomes tested. However, there was a high level of diploidy, with XY, XX, and YY constitution. Tetraploid sperm (XXYY) were also noted.CONCLUSION(S): Semen analysis revealed a high incidence of abnormal morphology and increased diploidy. It may be important to perform FISH testing, to verify increased diploidy in sperm, in men whose wives have had partial moles. These couples could be informed of the option to have preimplantation genetic diagnosis as a means to distinguish between diploid and triploid embryos arising from fertilization of a haploid egg by diploid sperm.