Meiosis was studied from pachytene and onwards in two clones of S.t. ssp. phureja. At pachytene the bivalents of S.t. ssp. phureja appeared to be morphologically very similar to those of S.t. ssp. tuberosum cv. Gineke. Cross-shaped quadrivalent configurations at pachytene confirmed the presence of a heterozygous interchange. From the configurations at pachytene it was identified that the short arm of chromosome 3 and possibly one of the arms of chromosome 12 was involved in the interchange. In addition, several abnormalities were observed: these included the occurrence of loops in eu- and heterochromatic parts, non-homologous pairing and centromere associations between different bivalents.