Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an independent risk factor for CVD and has been proposed as a marker of vascular inflammation. Polyunsaturated n-3 fatty acids (FA) and several n-6 FA are known to suppress inflammation and may influence Lp-PLA2 mass and activity. The associations of n-3 and n-6 plasma FA with Lp-PLA2 mass and activity were analysed using linear regression analysis in 2246 participants of the Multi-Ethnic Study of Atherosclerosis; statistical adjustments were made to control for body mass, inflammation, lipids, diabetes, and additional clinical and demographic factors. Lp-PLA2 mass and activity were significantly lower in participants with the higher n-3 FA EPA (β = - 4·72, P< 0·001; β = - 1·53; P= 0·023) and DHA levels (β = - 4·47, β = - 1·87; both P< 0·001). Those in the highest quintiles of plasma EPA and DHA showed 12·71 and 19·15 ng/ml lower Lp-PLA2 mass and 5·7 and 8·90 nmol/min per ml lower Lp-PLA2 activity than those in the first quintiles, respectively. In addition, lower Lp-PLA2 mass and activity were associated with higher levels of n-6 arachidonic acid (β = - 1·63, β = - 1·30; both P< 0·001), while γ-linolenic acid was negatively associated with activity (β = - 27·7, P= 0·027). Lp-PLA2 mass was significantly higher in participants with greater plasma levels of n-6 linoleic (β = 0·828, P= 0·011) and dihomo-γ-linolenic acids (β = 4·17, P= 0·002). Based on their independent associations with Lp-PLA2 mass and activity, certain n-3 and n-6 FA may have additional influences on CVD risk. Intervention studies are warranted to assess whether these macronutrients may directly influence Lp-PLA2 expression or activity.