Diarrhoea is still a problem for public health in developing countries, especially in Indonesia. The incidence of diarrhoea primarily affects infants in the 6-24 months age group because the infants start to obtain non-milk supplementary food in this age group, consequently increasing the risk of getting infected due to the consumption of germ-contaminated food. Breast milk contains required antibodies, and breastfed infants tend to have a more stable immune system than formula-fed infants. Most infant formulas are made from cow's milk or soybean. Formula feeding is indicated for those unable to obtain breast milk, and infant formula is often used as supplementary milk for mothers who cannot provide adequate breast milk. This study is aimed to determine the differences in the incidence of diarrhoea between 6-24 months old infants with exclusive breastfeeding versus infants with non-exclusive breastfeeding in the same age range. The researcher is analytical research with a case-control design, involving 60 infants as the research sample. Data were analyzed by using SPSS with a Chi-square test. The research results show differences in the incidence of diarrhoea between 6-24 months old infants with exclusive breastfeeding versus infants with non-exclusive breastfeeding in the same age range. Key words: Diarrhea, 6-24 months age, Exclusive breast milk, Non-exclusive breast milk.