The presence of monosomy 7 in 30 cases of bone marrow failure was examined in this study using fluorescent in situ hybridization (FISH). Twelve patients had acquired aplastic anemia; eight with Fanconi anemia and ten recently diagnosed acute myeloid leukemia (AML) as a patient control group, as well as ten age matched healthy children (control group). Monosomy 7 cut-off value was 2.9%. Monosomy 7 was found in 12/20 (60%); of aplastic anemia patients, five of 12, (41.7%), were acquired aplastic anemia, seven were Fanconi anemia7/8 (87.5%).There was an observed highly significance difference (P value =0.0001) between Fanconi anemia patients and the healthy control while there was no significance difference between Fanconi patients and AML patients. In acquired aplastic group there was no significance statistical difference between it and the healthy control, but there is a significance decrease in the percent of monosomy 7 between acquired aplastic patients and both AML and Fanconi patients. Among acquired aplastic group viral etiology and severity of aplastic anemia are risk factors for evolution of monosomy 7.During the study 2 cases of Fanconi anemia evolutes to MDS as a late complication with high percent of monosomy 7.All cases showed positive monosomy7 results considered high risk patients for evolution of MDS or AML and need meticulous follow up. Key words: aplastic anemia –monosomy 7.