Summary Blood culture is a vital investigation and can be the first step in obtaining a definitive diagnosis in a patient with presumed sepsis, but can also have serious adverse consequences for the patient. The aim of this study was to evaluate the extent of the blood culture contamination problem at the Lancashire Teaching Hospitals (LTH) and to assess the impact of the introduction of a new blood culture collection kit on the contamination rate. Blood culture contamination rate at the LTH before the introduction of the blood culture collection kit was 9.2%. A fall in contamination rate was observed after kit introduction, to 3.8%, a proportion approaching the American Society of Microbiologists’ recommended standard of ≤3%. The reduction in contamination was associated with an unintended, yet sustained, reduction in the total number of blood culture sets collected and an unwanted reduction in the number of genuine Gram-negative bacteraemias. This reduction may reflect education and training issues at the time of the introduction. In the era of ‘route cause analyses’, it may also reflect fears by junior colleagues of the consequences of being found responsible for a blood culture contaminant. The study recommended continuing with the blood culture kit, but ensuring regular training and education sessions, carried out in a non-blame manner.