SUMMARYGiven the increasing prevalence of metabolic syndrome (MetS) in males of reproductive age, the objective of this prospective casecontrolled study was to investigate the impact of subacute systemic inflammation associated with MetS on seminal cytokines and standard sperm parameters in comparison with healthy men. Between 2011 and 2014, we recruited 27 patients with MetS out of 41 obese patients screened from an internal outpatient clinic. Twenty-seven age-matched healthy controls were enrolled from 54 men requesting vasectomy in a urological outpatient clinic. A multiplex analysis was performed to quantify simultaneously the level of 30 cytokines (Eotaxin, FGF, Fraktalkine, GCSF, GMCSF, Granzyme A, IFN-c, IL-1a, IL-1b, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12p70, IL-13, IL-17A, IL-21, IP-10, I-TAC, MCP-1, MIG, MIP-1a, MIP-1b, RANTES, TNF-a, and VEGF) in each 50 lL of blood and seminal plasma during the andrological work-up. Semen analysis was performed according to the WHO (Global status report on noncommunicable diseases, 2010) recommendations, including standard sperm parameters as well as peroxidase-positive leukocytes and polymorphonuclear elastase. Blood levels of C-reactive protein, interleukins 6 and 10 were elevated in MetS (p > 0.001). Two-way hierarchical cluster analysis showed characteristic cytokine networks in semen greatly differing from those in blood, but not between MetS and controls. No deterioration of semen analysis was evident in men diagnosed with MetS. Our results suggest that there is no transmission of the systemic inflammation associated with MetS into semen based on cytokine profiles and that MetS does not impair standard semen parameters to a clinically significant extent.