The behaviour of a spontaneous interchange heterozygote inCapsicum chinensehas been analysed. It showed 44.4% pollen sterility and PMCswith 10II+ 1 ring or chain of four chromosomes or 10II+ 1III+ 1Ior 11II+ 2Iin addition to cells with 12II. The somatic chromosome set of 2n= 24 has one homomorphic and a second heteromorphic pairs of satellited chromosomes. It is inferred that the smaller member in the heteromorphic pair is the normal chromosome and that during the interchange its homologue has shifted a very short satellited segment to a centric segment of a nonhomologous chromosome, bearing no satellite, to form the longer chromosome in the heteromorphic pair.