This study pretends to evaluate differences on macroinvertebrate communities before and after wildfires occurred during 2002 and 2003 in a Mediterranean region of southern Portugal. Macroinvertebrates of four sites located along three different streams were sampled during spring, before (2001) and after wildfires (2006). Samples, covering all the existent habitats, were taken with hand nets and surbers (0,5mm mesh size). A Principal Component Analysis of the macroinvertebrate relative frequencies of all samples was performed, showing in the first axis (40 percentage of explanation) an opposition between upstream and downstream sites. To the second axis (17 percentage of explanation) an opposition between sites before and after wildfires is detected mainly to the downstream sites. A second Principal Component Analysis of the differences between macroinvertebrate relative frequencies before and after wildfires for each site confirmed the opposition between upstream and downstream sites. Baetis sp. and Tanytarsini are the most responsible for upstream differences while to the downstream sites, the most important differences are related to Limonidae Chironominae and Corixidae frequencies. Although the observed differences before and after the wildfires, these streams are located in a Mediterranean region where accentuated annual variability is normal, being difficult to split this influence from wildfire disturbances.