Parasites can interact with environmental pollution in different ways. On the one hand, parasites can interfere with established bioindication procedures owing to their effects on the physiology and behaviour of the host. This could lead both to false-negative and false-positive indications of pollution. On the other hand, parasites can be used as effect indicators and as accumulation indicators because of the variety of ways in which they respond to anthropogenic pollution. Although we are just at the very beginning of an extremely important field of interdisciplinary research, the fast-growing number of papers obliges this state-of-the-art summary.