This is a report from the laboratory of Dr. John F. Enders of the successful propagation of an egg-adapted strain of measles virus in cultures of chick-embryo cells throughout 24 serial passages. While the technical details will be of interest to experts in the field, the authors indicate that the quantities of measles virus which can be produced in chick cells is such that fluid from cultures of this type might provide appropriate material for the preparation of vaccine. The technique reported also has possible application to the assay of infectivity and the titration of antibodies for diagnostic and epidemiologic investigaton.