The cariogenic effect of Enovid (98.5% norethynodrel and 1.5% mestranol) and of progesterone was determined by subcutaneously injecting two groups of female weanling rats with 0.5 mg Enovid or 1.25 mg progesterone twice weekly for 8 weeks; controls received vehicle only. Upon sacrifice, submandibular glands were examined histologically and molars were examined for the number and severity of carious lesions. Severity of carious lesions was arbitrarily score as 2,3,or 4 according to the degree of decay. Enovid treatment increased the number and severity of dental caries; Enovid also decreased the number and diameter of submandibular granular tubules. Progesterone administration also decreased the number and diameter of submandibular granular tubules, but the effect on dental caries was not significant.