An investigation of Lophomonas blattarum infection in Periplaneta americana in Wuhan City were conducted. A total of 110 P. americana were dissected and the intestines were separated. The intestines were washed with 0.6% saline and the washing solutions were smeared on slides. The slides were stained with Giemsa stain and observed under a microscope (x1000). Out of 110 intestine washing solution samples, 44 were suspected of L. blattarum infection. The parasite was oval or pyriform in shape and 20-40 microm in size. A tuft of flagella extended down the central axis of the parasite and a trumpet-shaped calyx enveloped the flagellar area and the nucleus. An axostyle was slender and pointed posterior ends. Based on the above morphological characteristics, the parasite was identified as L. blattarum. The results showed that the infection rate of L. blattarum in P. amerivana in Wuhan City was 40.0% (44/110).