Most infective juveniles of DD-136 (Neoaplectana, Steinernematidae) were found to contain cells of Achromobacter nematophilus Poinar & Thomas in the ventricular portion of their intestinal lumen. In two instances, anterior intestinal cells of the infective juveniles were found to contain bacterial cells, presumably those of A. nematophilus. When the infective stage penetrated into the body cavity of a suitable host, the bacteria were released through the anus and multiplied rapidly in the host's body, resulting in a fatal septicemia.