Heptachlor is a chlorinated dicyclopentadiene insecticide, which is persistent in the environment and accumulates in the food chain. Its use is severely restricted under the Stockholm Convention on Persistent Organic Pollutants, and it is also subject to global restriction under the Rotterdam Convention on Prior Informed Consent. This Concise International Assessment Document (CICAD) evaluates the scientific literature on the health and environmental effects of heptachlor, providing an update of the information previously considered by international bodies.