Surveys in Indonesia say that half a million children still like to wet the bed. There are about 20% of children under five do not do toilet training and 75% of parents do not view such conditions as a problem. The proximity of parents' interactions with children in toilet training will make children feel safe and confident. Parents readiness factor plays an important role to train children and requires a gradual process and a long time. The purpose of this research is to know the correlation of parents readiness with the ability of toilet training in children aged 18 - 36 months. The research design used was analytical with Cross Sectional approach. Free variable is the readiness of parents, while the dependent variable is the ability of toilet training children aged 18 - 36 months. The sample in this research is mother who have children aged 18 - 36 months. The data used are primary and secondary data. The data collection instrument used is a closed questionnaire. The data obtained were then analyzed by univariate analysis (frequency distribution) and bivariate analysis (Chi Squere). Result of data analysis show p <0,05 meaning there is significant relation and value of Odd ratio equal to 22 mean that mother ready in doing toilet training in child have chance of their child successfully do toilet training 22 times bigger. Conclusion There is a significant relationship between Parental readiness with toilet training ability in children aged 18-36 months.