AbstractBackground: chromosome 17 abnormalities are non-random cytogenetic events that occur in hematological and myeloid malignancies. Their prognostic impact is mostly related to alteration of tumor suppressor gene p53 by deletion or mutation. The aim of this study is to detect the frequency and types of chromosome 17 abnormalities and their prognostic effect in myeloid malignancies patients. Methods the study included 50 patients of newly diagnosed myeloid malignancies divided into three groups: group 1 included 28 AML patients, group 2 included 7 MDS patients and group 3 included 15 CML patients. All studied patients groups were subjected to history taking, clinical examination, routine laboratory investigations, conventional cytogenetic analysis and FISH for detection of chromosome 17 abnormalities. Results Chromosome 17 abnormalities were positive in 52% of myeloid malignancies patients; structural abnormalities were more frequent (40%) than numerical abnormalities (12%). Chromosome 17 abnormalities was detected in 67.9% of AML patients, 28.6% of MDS patients, and in 33.3% of CML patients. Conclusion Chromosome 17 abnormalities were frequent cytogenetic events that occur in various myeloid neoplasms and have poor prognostic impact related to alteration of tumor suppressor gene (p53)