Dear Editor,rnComplex chromosome rearrangements (CCRs) are structural aberrations involving at least three chromosomes with three or more chromosomal breakpoints.CCRs are very rare events in the human population.As reviewed by Pellestor et al.,1 less than 255 cases of CCRs involving three or more chromosomes have been reported.In China,approximately 136 cases of CCRs,including 40 males with reproductive problems,have been reported up to the time this review was compiled.rnCCRs have been classified into three major categories,according to their structure:three-way exchange,double two-way exchange,and exceptional CCRs.The double two-way exchange is the simplest CCR,in which there is a coincidence of two separate simple reciprocal translocations or a reciprocal translocation with a Robertsonian translocation or an inversion.CCRs can be familial or de novo and may be balanced or unbalanced.Because balanced CCRs can lead to an unbalanced condition of the gametes or a meiotic disturbance,CCR carriers are at high risk of having a child with an unbalanced karyotype,spontaneous abortions,and infertility.In phenotypically normal individuals,female carriers of CCRs are frequently identified after giving birth to malformed babies or suffering from repeated miscarriages;2 whereas,most of the male carriers of CCRs are detected due to infertility problems arising from oligozoospermia or azoospermia.