Polymorphonuclear leukocytes (PMNLs) are an important contributor to inflammation and are thus a part of the pathophysiology of many human diseases. We assessed the effect of fish oil on PMNL inflammatory potential by measuring chemiluminescence and Superoxide production before and after six weeks of daily cod liver oil ingestion by healthy volunteers. Phagocytosing PMNLs demonstrated a 27% decrease in chemiluminescence (P < 0.05)="" and="" a="" 64%="" decrease="" in="" superoxide="" production="">P < 0.01),="" following="" the="" cod="" liver="" oil="" supplementation.="" analysis="" of="" pmnl="" and="" platelet="" fatty="" acids="" revealed="" the="" appearance="" of="" eicosapentaenoic="" acid="" and="" a="" significant="" decrease="" in="" arachidonic="" acid="" in="" both="" types="" of="">