The bacterial parasite Bdellovibrio bacteriovorus was studied in the process of its interaction with the host bacterium Pseudomonas fluorescens. As has been shown by time-lapse microcinematography, along with the normal growth of B. bacteriovorus in the periplasmatic space of the host bacterium, occasionally (4--5%) the parasite is located in the cytoplasm where the complete stage of its intracellular growth takes place with the release of progeny.