The present study describes the antimicrobial activity of 2 extracts of Palustriella commutata (Hedw.) Ochyra, collected from the Sündiken Mountains, Eskişehir, Turkey. These extracts were first prepared with acetone and methanol solvents under reflux. The antimicrobial activity of the extracts was then assessed using the disc diffusion method against 11 bacteria, 1 yeast, and 8 moulds. The antimicrobial test results revealed that the acetone extract had a potential activity against 9 test bacteria. While some gram-positive bacteria tested were sensitive (Bacillus mycoides, B. cereus, B. subtilis, and Micrococcus luteus), all gram-negative bacteria tested (Klebsiella pneumoniae, Yersinia enterocolitica, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter aerogenes) were sensitive to the acetone extract. Both extracts were inactive against yeast and mould strains. The results presented in this paper suggest the possibility that P. commutata possesses a new antimicrobial compound that has an effect against gram-negative and gram-positive bacteria. © TÜBİTAK.