In the Iberian Peninsula and Balearic Islands there arc several bioclimatic regions which result in many different and fragmentary landscapes. Results obtained from monitoring 18 localities in Spain allow an outline of the aeropollen dynamics of some of these environments. The major pollen types are: 1. trees: Pima, Qvercus, Olea, Cupressaceae, 2. shrubs: Corylus, Pistacia and 3. herbs: Poaceae, Urticaceae, Chenopodiaceae-Amaranthaceae, Plantago and Asteraceae. In some locations Alnus, Artemisia, Buxus, Betula, Castanea, Eucalyptus, Populus, Ulmus, and Ephedra also have to be considered. Quantitatively, pollen from trees predominates over that from herbs and shrubs, although at some localities this trend varies. The first pollen grains found in the weekly atmospheric analyses arc from trees (winter). In spring tree pollen grains share the atmosphere with herb pollen. For this reason it is usual to find peak values of pollen content in the atmosphere during this part of the year, while winter and autumn arc characterized by low pollen counts. © 1991, Taylor & Francis Group, LLC.