Burrowing nematodes (Radopholus similis) are among the most serious nematode pests affecting banana and plantain (Musa spp.). In Uganda, bananas, which are known locally as "matooke", are the main staple. Radopholus similis populations collected in four banana-growing locations (Namulonge, Mbarara, Ikulwe and Mukono) were cultured monoxenically on carrot discs, and we compared the variability in reproductive fitness and virulence (as a function of time and inoculum level) of different populations of R. similis from Uganda. Their level of pathogenicity was determined by assessing the nematode reproductive ratio; that is, final population divided by the initial population. These in vitro experiments showed that the R. similis population from Mbarara had the highest reproduction ratio, while the population from Mukono had the lowest reproduction ratio. This assessment along with pathogenicity experiments on host Musa plants provides a means for defining pathogenicity groups among R. similis populations. © 2013 Copyright Taylor and Francis Group, LLC.