In a large number of allergic individuals, inhalant allergens are important causative and triggering agents in respiratory allergies. It is essential to survey the pollen and mold around the patient’s environment for the diagnosis and treatment of airborne allergy. Rotorod samplers were installed at well-ventilated places in seven collecting stations in Seoul, the capital of Korea, which has a population of 12 million. Airborne particles carrying allergens were collected daily from each station for 2 years (1 October 1995 to 30 September 1997). After being stained with Calberla’s fuchsin, they were identified, counted and recorded. The weather in Seoul was also recorded. Pollen was found from the middle of February through to the end of December. The peak date for pollen was 12 May (peak mean daily count: 701 grains/m3/day) and for mold it was 23 June (peak mean daily count: 936 spores/m3/day). Alder, birch, pine, oak, maple, elm, juniper, willow, and gingko trees were prevalent during the tree season, lasting from the middle of February to late July. Then sagebrush, ragweed, Japanese hop, and pigweed followed during the weed season, which lasts from the middle of July to the end of December. In skin prick test results, house dust mite was the most common positive allergen in Seoul, followed by cockroach. Among the pollens, mugwort was the most common positive, followed by ragweed mix, alder, birch, and grasses mix. Among the molds, there were high counts of Cladosporium and Alternaria during the year, excluding January. Ascospore of Lepto-spheria was highest during the monsoon season.