Most pathogens invading the human body are attacked by the host immune system directly following entry and usually also during most stages of the disease, especially when they are in contact with the blood. However, pathogens have developed an effective battery of specific strategies to overcome immune defense. This, far from being complete, review concentrates on evasion of pathogens by avoiding recognition or eradication by complement. The latter is achieved by removal of complement either by shedding it off the microbial surface, by consuming it away from the target membrane or by destroying it. Alternative procedures of avoiding eradication are the inhibition of complement activation or the employment of complement proteins via several highly sophisticated mechanisms, including the imitation of complement-like proteins (molecular mimicry).