JWH-398 is an analgesic chemical from the naphthoylindole family, which acts as a cannabinoid agonist at both the CB<sub>1</sub> and CB<sub>2</sub> receptors. It has mild selectivity for CB<sub>1</sub> with a K<sub>i</sub> of 2.3 nM and 2.8 nM at CB<sub>2</sub>. This synthetic chemical compound was identified by the EMCDDA as an ingredient in three separate "herbal incense" products purchased from online shops between February and June 2009. It was discovered by, and named after, John W. Huffman.
In the United States, JWH-398 is a Schedule I controlled substance.