There are discrepancies in the retrospective studies published in literature of whether or not bacteraemia could lead to false positivity of 1,3-β-D (BG) glucan assay. We performed, for the first time, a prospective study evaluating the role of bacterial bloodstream infection to the reactivity of BG assay. Twenty-six episodes of bacteraemia that occurred in high-risk haematological patients were included in our study. Consecutive BG levels >80 pg ml−1 were required for test positivity. Only 2 of 26 patients were BG positive – both with IFDs. Thus, we prospectively did not prove bacteraemia as the source of cross reactivity of BG assay in haematological patients.