Bronchial asthma is a common clinical problem in the United States, affecting about 10 million people, or about 4% of the population. The occurrence of childhood asthma has increased in frequency, severity and rate of admisssion to hospitals in the U.S. This is in part due to greater recognition of asthma by families and health care professionals, but also appears to represent a true increase in disease, likely due to increased environmental pollution and allergens. This proposal outlines the first effort to identify prevalence, geographic distribution and seasonal patterns of childhood asthma using an asthma registry which is being initiated in Iowa. Rates of specific treatments will be calculated, based upon health care claims from three major insurers in Iowa. Secondary data representing environmental, climatological, socioeconomic and other patient factors will be analyzed to characterize their influence upon the prevalence and severity of childhood asthma in Iowa communities.