AbstractPolyploid strains ofCandida scottiishow a higher spontaneous and UV‐induced variability in accumulation of riboflavin in the medium than the original haploid strain. UV irradiation affects the formation of variants and induces those which accumulate more riboflavin than any of the most productive variants resulting from spontaneous variability. In the polyploid strains the frequency of plus‐variants increases. Therefore, polyploid strains ofC. scottiiare advantageous for selection proces