Summary Observations on the re-isolation of Cryptococcus neoformans from an aviary in a zoological garden have been reported and discussed.. The pathogen could be recognized on niger-seed creatinine agar within 3 days of inoculation of test samples of avian excreta. Using niger-seed creatinine medium in combination with the membrane filtration technique, it was estimated that the samples contained 9.5 × 10 7 cells per gram of dry fecal matter. It has been suggested that this simple procedure deserves greater attention in investigations aimed at gaining a better insight into the ecology of C. neoformans. The technique promises to be particularly suitable for screening of C. neoformans in those substrate which carry only a few cells of the fungus or else have an overwhelming number of other microorganisms.