The accurate detection and quantitation of cytokines in serum are important in the study of disease mechanisms, pathogenesis, and treatment. Serum cytokines can reflect processes that are occurring at the cellular or tissue level and thus provide a means of indirectly monitoring these processes. Multiplex detection of cytokines allows the simultaneous measurement of multiple cytokines in a sample, increasing the efficiency of measuring the cytokines while reducing the serum sample volumes required for the testing. Two commercially available multiplex platforms were evaluated (Pierce SearchLight and Meso Scale Discovery), using multiplexes capable of simultaneously detecting eight cytokines. The cytokines analyzed in this study were gamma interferon, vascular endothelial growth factor, tumor necrosis factor alpha, interleukin-6 (IL-6), macrophage inflammatory protein 1beta, monocyte chemoattractant protein 1, IL-12p40, and IL-4. The range of quantitation of the platforms, the recovery of spiked cytokines, and the detection of the cytokines in serum samples from subjects with ulcerative colitis, Crohn's disease, rheumatoid arthritis, and psoriasis were examined. The findings showed that the detection of the cytokines was highly dependent upon the platform, with the consistency of the detection of cytokines across platforms being dependent upon the cytokine being analyzed. A careful examination of platform assay performance must be made prior to utilizing multiplex platforms in a study. While some cytokines will give similar patterns of results across platforms, others will be highly variable. The use of the same platform within a study or across studies where data will be compared is advised.