THE statement that “only two homologous chromosomes can pair at one time” is one of the most basic of cytogenetic principles. It is founded on observations of meiosis in triploid and tetraploid organisms1–7 which have suggested that if three homologues are present, they will occur as a pair and a single unpaired chromosome. If four homologues are present, the chromosomes may exchange pairing partners, but they occur as two separate pairs. We now present evidence that the chromosomes of the triploid chicken are not bound by these rules and are capable of “triple pairing”.