Abstract: Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is one of the most threatening diseases in soybean, the most important agricultural crop in Uruguay. Resistance to ASR is conditioned by major genes called Rpps. So far, at least 12 Rpp genes and/or alleles have been identified and mapped to seven loci in the soybean genome. To enhance genetic improvement and reduce yield losses in Uruguay, it is essential to know the pathotypes that interact with Rpp-carrying soybeans, their dynamics and diversity. Five commercial fields were sampled in different regions of the country during two seasons in order to determine the number of pathotypes to which soybeans are locally exposed. Three to 19 single-lesion isolates per field were obtained. Based on the number of uredinia per lesion and the sporulation level, avirulent/virulent phenotype was determined for each isolate by inoculating onto a differential set. Twenty-eight pathotypes were differentiated from a total of 50 isolates, 17 were unique, and 11 were recurrently isolated up to five times. The most frequent pathotype was found in one field only, while several pathotypes were shared among fields. Mayor genes Rpp1-b, Rpp5, and Rpp6 had resistant interactions with many of the isolates, while Rpp1-b and the soybean line with Rpp2, Rpp4, and Rpp5 stacked genes showed resistance to all isolates. In contrast, Rpp1 and Rpp3 showed susceptible reactions to all isolates. Pathogenic variability was higher within fields than among fields; thus, soybean cultivars can be exposed to up to 13 different pathotypes within a single field. This high diversity should be considered when breeding for resistance to this pathogen; thus, pyramiding mayor genes and introducing horizontal resistance should be considered. © 2022, The Author(s), under exclusive license to Sociedade Brasileira de Fitopatologia.