A preceding untargeted metabolic fingerprinting approach in our lab followed by targeted fatty acid analysis revealed alterations in arachidonic acid metabolism in samples derived from a diet-controlled smoking cessation study in which compliant subjects ( N = 39) quit smoking at baseline and were followed over the course of 3 months. Consequently, urinary eicosanoids were evaluated by means of a validated LC-MS/MS method. A significant decrease was obtained for the prostaglandins PGF2α, 8-iso-PGF2α, thromboxane 2,3-d-TXB2, and leukotriene E4 upon quitting smoking. These findings indicate a partial recovery of smoking-induced alterations in the eicosanoid profile due to a reduction in oxidative stress and the inflammatory response.