Pollen is very important causing factor for allergy such as allergic rhinitis, allergic conjunctivitis, and asthma, and pollen allergy has a remarkable clinical impact all over Korea. The main pollination period covers about half the year, from spring to autumn, and the distribution of airborne pollen taxa of allergological interest is related to pollen season dynamics. Korean academy of pediatric allergy and respiratory diseases (KAPARD) has evaluated the pollen characteristics and nationwide pollen count for over 10 years since 1997. Airborne particles carrying allergens were collected daily from nationwide 8 stations (Seoul, Guri, Cheongju, Daegu, Kwangju, Busan, Kangneung, and Jeju) by using 7 days-Burkard sampler (Burkard Manufacturing Co Ltd, Hertfordshire, UK) in South Korea (July 1, 1997-June 30, 2007). They were counted and recorded along with the meteorological factors daily. Tree pollen is a major airborne allergen in spring, grass is most common in summer, and weed pollen is major pollen in autumn in Korea. There has two peak seasons for pollen allergy, as summer and autumn. There is some evidence suggesting that the prevalence of allergic diseases in Korea has been on the increase in the past decade. However, recent findings of the phase I and II studies of the international Study of Asthma and Allergies in Childhood (ISAAC) study showed the absence of increases or little changes in prevalence of asthma symptoms and diagnosis rates in Korea, whereas the prevalence of allergic rhinitis and atopic dermatitis were increased. We reported the evidence that sensitization rate to weed pollen has been increased yearly since 1997 in childhood. Climate change and air pollution must be the major causing factors for the increase of pollen counts and sensitization rate to pollen. Climate change makes the plants earlier pollination and persisting pollination longer. In conclusion, data on pollen count and structure in the last few years, the pathogenetic role of pollen and the interaction between pollen and air pollutants with climate change gave new insights into the mechanism of respiratory allergic diseases in Korea.