Minced chick-embryo tissue, bathed in a lactalbumin growth medium and planted on a modified Zinsser's agar medium, supported excellent growth of Coxiella burnetii. Titration of the viable rickettsial content of samples taken during the growth curve indicated proliferation of rickettsiae. Spectrophotometric measurements of purified suspensions of rickettsiae isolated from cultures incubated for varying periods also showed that growth had occurred. Other ancillary observations indicated that the final yield in mouse- or chick-embryo cultures was comparable to that produced in yolk-sac cultures.