Plasmid pE194 determining macrolide-lincosamid-streptogramin B resistance could be eliminated with novobiocin and coumermycin A1 in Bacillus subtilis and Staphylococcus aureus. In both organisms the curing effect depended on the temperature. In the case of Staphylococcus aureus it increased very much at high temperatures, while in the case of Bacillus subtilis only a moderate increase could be observed. The curing activity of coumermycin was substantially weaker than that of novobiocin in both bacteria. This difference decreased at higher temperatures only in Staphylococcus aureus. In Bacillus subtilis the curing with novobiocin could be antagonized with coumermycin in accordance with the growth experiments reported previously.