We have synthesized twelve new ionic liquids composed of an imidazolium-based cation in combination with an anion that shows antiobiotic or analgesic activity. These "BIOnic Liquids" have been tested towards their antibiotic activity in a standardized microbiological assay. A surprizingly large number of compounds shows high activity towards a set of bacteria which cannot be explained as simple cumulative effects. The general concept opens up completely new possibilities for the future development of pharmaceutically active compounds.