In Vahabi’s research the most frequent extracted bacterium from cockroaches’ external body surface was Escherichia coli and the second was Proteus, which were potential pathogens[3]. In the same researches, the bacteria species were isolated from the cockroaches’ body surface as mostly identified in our investigation[10,13]. In this study, twenty two bacteria species were isolated from the cockroaches’ alimentary tract. In this regard, the body surface of E.coli was the most frequently isolated from cockroaches’ intestines while the contamination approved to Morganella morganii.