Gram positive (Bacillus cereus, B. subtilis), Gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria, and Candida albicans as a representative of fungi were used for screening the in vitro antimicrobial activity of diarylamines in the 2,3,5-trimethylbenzo[b]thiophene series bearing different substituents, synthesized by us using the palladium-catalyzed C-N coupling methodology. The minimal inhibitory concentration (MIC) and structure-activity relationships (SARs) were evaluated.