Cultures of Chloropseudomonas ethylica strain 2-K obtained from several laboratories were examined. All cultures examined to date in this laboratory contained nonmotile, green, photosynthetic bacteria (Chlorobiaceae) identical to published descriptions of Chlorobium limicola and at least one colorless, motile bacterium. All attempts to isolate motile photosynthetic bacteria corresponding to published descriptions of C. ethylica from such cultures have been unsuccessful. Several physiological characteristics previously ascribed to C. ethylica 2-K are expressions of mixed cultures rather than the property of a single species.