Chickens of various ages and breeds were vaccinated subcutaneously with Newcastle disease live-in-oil vaccines. These vaccines were prepared immediately prior to the vaccination by mixing the lyophilized live vaccine with the oil adjuvant, which was kept at room temperature. The live-in-oil vaccines were shown to be 30-50 times more effective in efficacy tests than either the same vaccines reconstituted in water or killed-in-oil vaccines. In addition to its biological advantage, the method of preparation of live-in-oil vaccine saves the expensive space of cold storage and shipment necessary for conventional killed-in-oil vaccines.