SummarySomatic chromosome doubling of potato dihaploids was achieved by culturing callus from leaf pieces derived from glasshouse andin vitrogrown plants. The glasshouse‐grown leaves produced better callus on average but there was no significant difference between the average number of plantlets per callus regenerated from the two types of material.Mixtures of 2x and 4x plants were obtained from callus culture and the proportions of each ploidy type varied with the dihaploid genotype. Leaflet length/breadth ratios were chiefly determined but ploidy but there was variation within ploidy groups. There were also differences in blight and cyst nematode resistance between tetraploids derived from the same dihaploi