To analyse if hydrocortisone could modify the in vitro susceptibility of Aspergillus fumigatus to antifungal drugs, we developed a procedure to test the susceptibility of an A. fumigatus strain to amphotericin B and itraconazole, grown in the presence and in the absence of hydrocortisone. Conidia were germinated in the presence or the absence of hydrocortisone in Czapek medium without antifungal drug. A dilution of these cultures (5 × 103 conidia ml−1) was spread onto Czapek-agarose plates containing both antifungal drug and hydrocortisone. The cfu per plate were enumerated and compared. A therapeutic concentration of hydrocortisone induced a significant increase in the susceptibility to itraconazole. Conversely, the susceptibility to amphotericin B was not significantly modified when this antifungal drug was associated with hydrocortisone.