The inheritance of supernumerary spikelets was found to be controlled by two recessive genes with evidence for the possibility of a repressor(s) in crosses between normal and supernumerary spikelet wheats. In experimental lines with phenotypically normal heads but possessing the recessive supernumerary spikelet gene(s), increases in the number of nodes on the rachis (and hence the number of normal spikelets) fertility and grain number per head were found, as well as in the ‘normal’ Australian and American wheat cultivar Phoenix. This attribute has previously been suggested to be a way of increasing spikelet number in future wheat breeding.