Cultures of Bacillus subtilis release transforming DNA during the early exponential and stationary phases of growth. The pattern of release of transforming DNA was followed by measuring transformation in a system consisting of a non-transformable DNA donor and a differently marked transformable recipient. Transformation in this system seems to be at least as efficient as that induced by purified DNA. Fluorescence microscopy revealed that released DNA remained bound extracellular to intact cells. The release of DNA during early exponential growth seemed to be correlated with the cells' proneness to lysis; both DNA release and cell lysis were inhibited by chloramphenicol. In stationary cells, the release of DNA was neither correlated with a similar proneness to lysis nor inhibited by chloramphenicol.