Postoperative fungal infections may be caused by discharge of spores from contaminated air conditioning (AC) units. The filters of such units may act as a nidus for the growth of fungi. In this survey, filters of AC units in 25 operating theatres in India were evaluated quarterly over two years. The overall rate of fungal colonization of the AC filters was 26%. In addition, window-mounted AC units had higher fungal counts than wall-mounted AC units. We conclude that although the exact load of fungal spores necessary to initiate infections is unknown, AC units in operating theatres should be meticulously maintained and frequently monitored to minimize the chances of growth and proliferation of potentially pathogenic fungi. Data from this study also suggest that the design of the AC unit may play an important role in reducing fungal spore counts in the air of operating theatres in developing countries.