Background : Aneuploidy is a change in the number of chromosomes, either polysomy or monosomy. Trisomy 8 is the most common numerical abnormality in acute myeloid leukemia (AML). Aim of the study is to detect the prevalence of chromosome 8 aneuploidy in AML patients and analyze its impact on the different clinical and Hematological parameters. Subjects and methods: The study included 40 newly diagnosed adult AML patients. Presence of chromosome 8 aneuploidy was tested with the FISH technique. Results: Trisomy 8 was detected in 2 cases (5%) of de novo AML patients as a sole anomaly, monosomy 8 was detected in 1 case (2.5%) of AML patients. Also t (8; 21) was detected in 3 cases (7.5%). There was significant statistical difference between blast percentage in BM and in PB of both groups of patients, those with chromosome 8 aberration and those without (p=0.059) & (P<0.001) respectively. Conclusion: FISH is a reliable method for detection of trisomy 8, one of the most common numerical abnormalities in AML.