Brucella lipopolysaccharide (LPS), a non-classical endotoxin and outer membrane component, plays an important role in host?Brucella interactions. The survival of Brucella inside the macrophages is critical for Brucella pathogenesis. The differential effects of smooth and rough B. abortus LPSs on bovine macrophages, neutrophils and murine macrophages were studied and compared. B. abortus LPSs were isolated from rough (RB51) and smooth (2308) strains and were purified. Both rough and smooth LPSs were used separately and in combination to activate bovine macrophages, neutrophils and murine RAW264.7 macrophages. The lysozyme release test (LRT), nitroblue tetrazolium test (NBT), nitric oxide (NO2) assay and cytokine ELISA assay were used to measure LPS-mediated induction of lysozyme, reactive oxygen species, nitric oxide, pro-inflammatory and anti-inflammatory cytokines in LPS treated cells. Rough Brucella LPS from strain RB51 induced significantly higher levels of lysozyme, oxidative stress, nitric oxide and inflammatory cytokines in treated cells than did LPS from smooth Brucella strain 2308, or a combination of smooth and rough LPSs.