The aim of this work was to determine the incidence of sperm disomy in cases of male infertility with idiopathic severe oligoasthenoteratozoospermia (OAT) .Twenty five males were included in this study; fifteen primary infertile males with idiopathic severe oligoasthenoteratozoospermia and ten normal fertile males were taken as a control group. Each infertile patient was subjected to conventional semen analysis, hormonal assay including [FSH, LH, testosterone (T)], scrotal ultrasound and Fluorescent In-Situ Hybridization (FISH) was carried out on their semen samples. The fertile controls were subjected as well to conventional semen analysis and Fluorescent In-Situ Hybridization (FISH) on their semen samples. A significantly higher frequency for XX disomy (0.18 ± 0.04) and XY disomy (0.37 ± 0.13) was found in spermatozoa from oligoasthenoteratozoospermic patients (Group I) than in those from normal control (Group II) (0.10 ± 0.04) and (0.17 ± 0.03). There was highly statistical significant difference between the two studied groups; XX disomy (p < 0.0005) and XY disomy (p <0.0005). There was no statistical significant difference in the percentage of YY disomy (0.09 ± 0.26) compared to normal controls (0.11 ± 0.04); (p > 0.05). A comparison was made between cases with abnormal forms > 70% (Group Ia) and cases with abnormal forms < 70% (Group Ib) as regards the mean percentage of XX, YY, and XY disomy. There was no statistical significant difference in the percentage of XX, YY, and XY disomy between the two studied groups (p > 0.05). Another comparison was made between (Group Ia) , (Group Ib) and (Group II) as regards the mean percentage of XX, YY and XY disomy using one way analysis of variance (ANOVA) test. There was a highly statistical significant difference in the percentage of XX disomy between (Group I) either (Ia) or (Ib) and (Group II); (p < 0.001). There was no statistical significant difference in the percentage of YY disomy between (Group I) either (Ia) or (Ib) and (Group II); (p > 0.05).There was a highly statistical significant difference in the percentage of XY disomy between (Group I) either (Ia) or (Ib) and (Group II); (p < 0.001).In conclusion, our data show a significantly increased aneuploidy rate for sex chromosomes in severe OAT patients compared with men with normal semen parameters. These data should be taken into account, and relative risks estimated, whenever severe OAT patient is a candidate to undergo Intra Cytoplasmic Sperm Injection (ICSI).