ObjectiveTo investigate the violation and bacterial carriage state of cockroaches in wards of a hospital (1-11 storey),and provide scientific basis for carring out comprehensive measures to eliminate the pollution of cockroaches to medical environment.MethodsThe visual and paper sticky capture method were applied to investigate the harmful invasion of cockroaches . Cockroaches were stickily captured from each floor, and were randomly divided into 11 groups, each had 5, they were sent to the laboratory for bacterial isolation and culture, serological and biochemical testing with routine methods. Results228 houses in wards of a hospital building were investigated, the traces of cockroaches by visual method in 171 houses were found, the positive rate was 75.00%. There were 191 pieces of sticky cloth for sticking cockroaches, and the positive papers were 80 pieces, 243 cockroaches were captured, violation rate of cockroaches was 41.88%, density of cockroaches were 1.27 per paper. Opportunistic pathogens were detected on the surface and the bodies of 11 groups of cockroaches,among which the main pathogens were Proteus spp.(14 strains), Klebsiella pneumoniae(11), Escherichia coli(7), Enterobacter agglomerates(8), Pseudomonas aeruginosa(5), Acinetobacter baumannii(3).ConclusionCockroach is one of the factors contributing to hospital environmental surface pollution; regular killing of cockroaches and timely monitoring the environmental hygiene are important measures to prevent nosocomial infection.