The methanol extract of Anacardium occidentale stem bark was evaluated for activities against the lipopolysaccharide (LPS)-induced septic shock, as well as LPS-induced microvascular permeability in mice. Pre-treatment with Anacardium occidentale extract (25-200 mg/kg) caused a dose-dependent and significant (p < 0.05) reduction in the elevated levels of alanine and aspartate aminotransferases in the sera of d-galactosamine-primed mice injected with LPS. The highest dose of the extract studied (200 mg/kg) produced a 100% protection against death from sepsis. Pentoxifylline (100 mg/kg) and L-NAME (5 mg/kg) offered 100% protection against LPS-induced septic shock, and produced marked reduction in elevated levels of transferases. A dose-related inhibition of LPS-induced microvascular permability in mice was also produced by pentoxifylline, L-NAME and the extract.