Two ELISA methods are described for quantitation of rabies envelope glycoprotein in suspensions containing liver or inactivated virus. One of these methods is currently used for "in process" control at the production of inactivated rabies vaccine in our laboratory. The results obtained with the ELISA-test have been compared with those from the classical NIH-test for a number of freeze dried vaccine preparations. Although no perfect correlation was obtained good vaccine lots could easily be distinguished from poor ones. Using the ELISA-test already at the start of the production process predictions can be made on the quality of the final product. At such the ELISA-test may be considered as an improvement in the standardization of inactivated rabies vaccine production.