The aim of this study was to investigate whether blood cell membrane monounsaturated fatty acids were associated with inflammation and disease outcome in patients with multiple sclerosis. The fatty acid composition in peripheral blood mononuclear cell and red blood cell membranes from 26 patients and 25 controls were determined by gas chromatography. Results showed positive associations between C-reactive protein and C16:1n-7, C18:1n-7, and C24:1n-9 in membranes from controls only. In general, C18:1n-9 and C20:1n-9 showed inverse correlations, while C16:1n-7 and C18:1n-7 showed positive correlations with disease outcome. Multiple sclerosis has a known inflammatory component. There is scarcity of literature on the role of monounsaturated fatty acids in inflammation, but results from this study suggested an association in healthy subjects between monounsaturated fatty acids and C-reactive protein, even at physiologically low levels. This association was not found in the plasma from patients. Furthermore, the n-9 and n-7 fatty acids played different roles in disease outcome, and therefore warrant inclusion, together with polyunsaturated fatty acids when investigating the inflammatory aspects of the disease.