In the University Hospital in Göttingen, the spectra of fungal species in clinical specimens of respiratory secretions, bronchial secretions and urine were compared over periods of 15 months (10/87 to 12/88 and 1/91 to 3/92) before and after the introduction of fluconazole. The following changes could be demonstrated: 1. In all specimens analysed the number of Candida albicans isolates decreased, while the number of Candida tropicalis isolates remained almost unchanged. 2. During the observation period the number of Candida glabrata isolates doubled. In 1991 C. glabrata was second to C. albicans as the most common of all fungal isolates, appearing in 8.6% of all specimens. 3. The total number of Candida krusei isolates increased only slightly, but the rise in the number of isolates in bronchial secretions was statistically significant. 4. The prevalence of rarely isolated Candida yeasts, such as Candida guilliermondii, Candida lipolytica and Candida kefyr, and Candida isolates which were not further differentiated increased. 5. During the observation period the number of mixed cultures showed a fourfold increase. C. glabrata and C. krusei were associated in more than 75% of all isolates with C. albicans or C. tropicalis respectively. 6. The number of mould isolates increased. These changes in the spectra of fungal isolates are discussed with respect to the broad therapeutic and prophylactic usage of fluconazole in the University Hospital of Göttingen.