RESUMEN
<p><b>OBJECTIVE</b>To determine a complex chromosomal rearrangement by advanced molecular cytogenetic techniques and analyze its clinical effect.</p><p><b>METHODS</b>A complex chromosomal rearrangement (CCR) involved in chromosomes 5, 16 and 20 in a 29-year-old male carrier was determined by chromosomal microdissection and multicolor fluorescence in situ hybridization (M-FISH), and family degree investigation was further performed.</p><p><b>RESULTS</b>The karyotype of the case was a complex chromosomal translocation among chromosomes 5, 20 and 16, and accompanied with a band of chromosome 20 inserted into chromosome 5. His mother and sister both had the same abnormal karyotype by familial investigation.</p><p><b>CONCLUSION</b>The combined use of M-FISH and chromosome microdissection is a powerful tool to determine CCR. The complex chromosomal rearrangement could be transmitted stably in the family, but still the carriers could give birth to a healthy baby by chance.</p>