Dialkylresorcinols are a class of antimicrobial natural products produced by a range of bacterial species. Semi-synthetic derivatization of two microbial dialkylresorcinols isolated from a Pseudomonas aurantiaca strain has yielded 21 derivatives, which were tested for antimicrobial activity, revealing several trends in their activity. The presence of aromatic and phenolic hydrogen atoms was crucial for activity, with all derivatives lacking these features possessing greatly reduced activity. On the other hand, derivatives with shorter alkyl chains at C-5 possessed lower MIC values, while one mono-fluorosulfated derivative showed significantly improved activity against several of the test strains.