The international study of asthma and allergy in childhood was designed for the epidemiological investigation of asthma, by means of a standardized methodology. It was started in 1989, as a consequence of very different results obtained in previous epidemiological studies, of which none could be considered as definitive. First, a standardized survey was performed, in order to determine the prevalence of asthma in the United Kingdom, New Zealand and Australia, and subsequently several countries joined them, Spain being one of them. The first objective was to discover the prevalence and severity of bronchial asthma in children who lived in different countries, and to compare the results. Also, it was intended to obtain baseline measurements, in order to assess future trends in asthma prevalence and severity, and to facilitate a base for a subsequent phase of etiologic investigation. For this study, following a protocol previously established, a written survey and a video-survey were given to children aged 13 and 14, and a written survey to the parents of the children aged 6 and 7. All the surveys were performed during the school year 1993-1994. A total of 8,087 surveys were conducted in 53 schools from Pamplona and neighbouring towns. Among the group of children aged 13 and 14, 5.3% had a crisis in the study period, whereas 4.4% suffered from an acute attack. This prevalence was not as high in children aged 6 and 7, for whom the percentages were 3.3% and 3.2%, respectively. We found lower prevalences in the two groups in relation to other countries, and we attribute this result, on one hand to the accessibility to doctors in our area, and on the other hand, to early diagnosis of the disease by specialists, periodic control and suitable etiologic treatment.