The aim of the work was to explore fatty acid composition of purslane seed water extract and its effect on the metabolic profile of murine peritoneal macrophages. Fatty acid composition was evaluated by gas chromatography massspectrometry. Collection of murine macrophages from the peritoneal cavity was done without preliminary sensitization. Reactive oxygen species generation was assayed by flow cytometry and nitroblue tetrazolium test. Phagocytic activity was evaluated by flow cytometry. Nitric oxide production was analyzed in cell supernatants by Griess reaction. Arginase activity was measured in cell lysates by standard colorimetric assay. Reactive oxygen species and nitric oxide production were significantly lower in murine macrophages simultaneously treated with purslane seed water extract and lipopolysaccharide in comparison to macrophages treated with lipopolysaccharide only. Also, the studied extract caused statistically significant increase in arginase activity of unsensitized peritoneal macrophages. That is consistent with the fatty acid content of this extract, since it contained comparatively higher proportion of unsaturated fatty acids exhibiting antiinflammatory properties, than saturated fatty acids known for their proinflammatory effects.