The incidence of dental caries /Is/ on deciduous molars in 1216 children aged 3 to 8 from Plovdiv has been studied. The results showed highest Is in the fissures of m1 and m2 and lowest Is on the smooth surfaces. The incidence of dental caries is getting higher with statistically significant differences in the lower jaw up to the 6th year and in the upper jaw up to 7th year of age. Is in the lower jaw is higher than that of the upper jaw only in the fissures.