Abstract The prevalence of yeast spores in the atmosphere of Cairo as determined by the Andersen air sampler, was investigated at four sites over a period of one year. The average total count showed seasonal periodicity. The maximum count was recorded in autumn and the minimum in summer. Eighteen species of yeasts belonging to 9 genera were recovered and identified. The opportunistic genera of yeasts represented by seven genera showed high percentage of the total count. The most prevalent genera Cryptococcus, Candida and Rhodotorula constituting, 26.6%, 19.9% and 17.9% respectively. Other genera of low count were Kluyveromyces (7.4%). Debaryomyces (4.3%) and Trichosporon (3.2%).