Background: Diarrhea is one of health problems in developing countries, including Indonesia. In Indonesia, diarrhea remains to be the main cause of death among children. Based on age range, toddlers (1-4 years old) has the highest diarrhea prevalence, reaching 16.7%. It rises the need for an effort to decrease mortality rate of children due to diarrhea. AIM: Determine the correlation between mother’s knowledge about diarrhea with diarrhea management in children aged 1-5 years old in Taman Tirto District, Kasihan, Bantul, Yogyakarta. Methods: This study was done in March 2017 using analytic observational approach. Study sampel is children aged 1-5 years old registered in daycares/kindergardens in Tamantirto, Kasihan, Bantul, Yogyakarta. Subjek were choosen by purposive sampling. Data collection was done by ask parents to fill in quesionnaires. Data analysis was done using Chi-Square/ Fisher test. Result: This study found 66 samples that were purposively choosen in groups from playground, kindergarten, and Satuan PAUD Sejenis in Taman Tirto, Kasihan, Bantul, Yogyakarta. Results showed that from 38 respondants (57.6%), mother's knowledge is considered in good category. From 34 respondants (51.1%), mother's behavior is considered in good category. There is a correlation between mother's knowledge about diarrhea with diarrhea management in children aged 1-5 years old, with significancy value of 0.007 (p<0.05). Conclusion: There is a correlation between mother's knowledge about diarrhea with diarrhea management in children aged 1-5 years old in Taman Tirto District, Kasihan, Bantul, Yogyakarta.