Although the relationship between asthma severity and exposure to airborne fungi has been well studied, little is known about the contribution of outdoor molds to the symptoms of children monosensitized to molds. In this study, we aimed to investigate the effect of outdoor mold spore concentrations on daily asthma and/or rhinitis scores in children monosensitized to molds. Nineteen children with asthma and/or rhinitis sensitized only to molds recorded their daily symptoms and PEF values to the diaries, from February 2005 to January 2006. Additionally, mold spores were measured daily using a Burkard 7-day recording volumetric spore trap in city atmosphere and compared with meteorological data. Total number of mold spores in atmosphere was found to be 352,867 spore/m(3) during the study period. Cladosporium (53%) was the most common encountered outdoor fungi, followed by Altemaria (29%) and 1-septate Ascospore (3%). Outdoor fungi concentrations were significantly correlated with mean monthly rhinitis score (r = 0.877, p < 0.001) and mean monthly asthma score (r = 0.831, p = 0.001), and mean monthly morning PEF (r = -0.741, p = 0.006) and evening PEF (r = -0.720, p = 0.008), and climatic conditions. The effect of outdoor fungi was highly evident on the symptoms of our patients with asthma and/or rhinitis monosensitized to molds.