Objective and Design: Since thirty years a major aria of cytogenetics investigation has been focused into the nature of genes defect and chromosomes abnormalities on association with subfertility and reproductive pathology. This study was conducted to assess the rate of chromosome aneuploidy in semen sample from a male how had 7 ART cycles with very bad embryo quality. During the last tentative the sequential culture was terminated without transfer. Multicolor Fluorescent In Situ Hybridization (M FISH) was used for chromosomes 8, 9, 13, 18, 21, X and Y to understand the possible male contribution in embryos development and ART failure. Materials and Methods: The semen was collected in the laboratory. After pure sperm preparation the sample presented 6.4 millions spz, 3.2 millions of round cells and 20% of mobility. After centrifugation, 2 times washing in distilled water, hypotonic treatment was done in natrium citrate solution, the sperm was fixed in carnoy and spread on slides. For DNA decondensation slides were treated with NaOH before probes hybridization. For aneuploidy assessment, specific probes for chromosomes 8, X and 13 were labeled directly using FITC, parallely for chromosomes 9, Y, 21 probes were labeled by Texas Red. For chromosome 18 a centromeric probe labeled with aqua was used. This combination of probe mix and hapten labeling allowed us to practice double and triple FISH permitting in each hybridization the use of one chromosome for the internal control. For FISH four different probes mix were used (8,9), (13,21), (X,Y) and (X, Y,18). The protocol of hybridization was done using the hybrite and completed by rapid washing and staining. Each hybridization was repeated twice and two different observers screened the slides. Results and Discussion: The results revealed severe unbalanced sex ratio using X and Y probes. The data from 3000 nuclei showed around 75% of X sperm and 20% of Y bearing. Triple color FISH, using X, Y and 18 probes confirmed this percentage. The disomy rate for chromosomes X and Y it was 1.4 and 1.3 respectively. After this preliminary results, the data of autosomes analysis demonstrated: 3.6% of disomy 13, 2.8% of disomy 21, 3% of disomy 8, 2.4% of disomy 9 and 3.7% of disomy 18. These disomy rates confirm an abnormal disjunction of the analyzed chromosomes compared to normal sperm. These aneuploidies or the total non-disjunction can explain the ART cycles failure by producing aneuploid or triploid embryos with severe disorders incompatible with embryo development and implantation. The question is, there are any mosaic germ cells (diploid/triploid) in the testis and if the answer is yes, what’s the ratio of this mosaicism? The analysis of testicular biopsy will be helpful to understand the behavior of chromosomes segregation during the spermatogenesis. This study illustrates the interest of sperm aneuploidy analysis in ART failure.