Conventional cytogenetics (CC) is proven as a diagnostic and prognostic factor 
in myelodysplastic syndrome (MDS). However, CC may be hampered by insufficient 
metaphase preparation and cannot analyze interphase nuclei. These problems are 
solved by using comparative genomic hybridization (CGH). The CGH was applied to 
samples from 45 patients with MDS, and the results were compared with CC and 
fluorescence in situ hybridization (FISH). The CC detected aberrations in 12 of 
45 samples, including chromosomes 3 (n = 1), 5 (n = 9), 7 (n = 2),8(n = 1), 18(n 
= 1),21 (n = 1), X (n = 1), and Y(n = 2). In one patient, loss of B and C group 
chromosomes and a marker chromosome were seen. The CGH revealed chromosomal 
imbalances in 18 of 45 samples, including chromosomes 5 (n = 11), 7 (n = 2), 8 
(n = 1), 18(n = 1), 20(n = 1), 21 (n = 1), X (n = 1), and Y (n = 2). All 
unbalanced aberrations found by CC were detected by CGH, too. In two patients, 
the CGH found additional aberrations and redefined the aberrations of the 
chromosomes of the B and C group in one sample. The FISH confirmed these 
aberrations. Additionally performed FISH for chromosomes 5, 7, and 8 gave normal 
findings in all patients found to be normal in CC and CGH. The CGH and FISH 
confirmed the results obtained by CC. All three techniques showed changes of 
chromosomes 5 and 7 as the most frequent aberrations, emphasizing the importance 
of these chromosomes in the development of MDS. Furthermore, the CC is proven as 
the basic technique for cytogenetic evaluation of MDS.