The appearance of detectable pro- as well as anti-inflammatory cytokines in the blood stream during sepsis is indicative of their exacerbated production. While pro-inflammatory cytokines are a prerequisite for initiating an effective anti-infectious process, they are also associated with harmful effects which can lead to multiple organ dysfunction and death. While anti-inflammatory cytokines are a prerequisite for controling the inflammatory response, they also lead to a depression of the immune system of patients. Furthermore, new evidence suggests that these so-called anti-inflammatory cytokines may not always behave as such. All in all, the analysis of the interplay between cytokines reveals that a very complex network of interactions is occuring and that pieces are still missing from the sepsis puzzle.