ObjectiveTo report the epidemiological investigation process as well as prevention and control measures for a suspected outbreak of healthcareassociated bloodstream infection(HAIBSI).MethodsAn epidemiological investigation on a suspected outbreak of HAIBSI in a hospital was carried out by means of clinical data investigation and onsite sampling, sources and transmission routes were determined, efficacy of prevention and control was evaluated.ResultsFrom April 21 to 28, 2014, a total of 6 patients in the neurological wards of a hospital suffered from chill and high fever, 4 cases were positive for peripheral blood culture (2 strains were Klebsiella pneumoniae, 1 strain was Acinetobacter baumannii and 1 strain was Enterobacter cloacae), HAIBSI was diagnosed. A total of 170 specimens were collected, the qualified rate of specimen detection result during centralized outbreak sampling period was lower than that after taking comprehensive prevention and control measures (64.91%［37/57］ VS 93.81%［106/113］, χ2=23.675，P=0.000）. Pathogens were mainly found in the area where most frequently touched by hands, bacteria on object surface in the vicinity of patients as well as bacteria on hands of caregivers were consistent with the pathogens causing  infection in patients. After comprehensive intervention was taken, no new case occurred, and 6 patients all recovered after treatment.ConclusionThis event is a suspected outbreak of HAIBSI, environmental contamination in wards and transmission through hands are the main sources and transmission routes. The implementation of targeted prevention and control measures of environmental decontamination and hand hygiene management can effectively control the outbreak of HAI.