modified yeasts and uses, particularly for the production of steroid derivatives.

Yeast strain having an activity of type 20a hydroxysteroid dehydrogenase (HSD 20a) has reduced characterized in that: -a inactivating genetic modification of the GCY1 gene, or -a inactivating genetic modification of the YPR1 gene, or -a inactivating genetic modification of the GCY1 gene and YPR1, with the exception of gcyD0 and gcyDD0 strains.