There is mounting evidence that a wide variety of compounds can have endocrine disrupting effects on humans and wildlife. However, investigations so far have focused primarily on exposure to human and other vertebrates, with invertebrate findings largely restricted to marine mollusks or to the ecdysteroid and juvenile hormone agonists as purposely synthesized endocrine disrupters for the pest management of insects. This article provides a brief description of the insect hormone system, a short sum-up of the relevant insect groups with aquatic life stages, and an overview of the additional evidence for endocrine disruption in aquatic insects from laboratory and field studies since 1999. In addition, the suitability of insects as sentinels for endocrine disrupting chemicals in aquatic ecosystems is discussed. Conclusions are drawn and research needs are defined.