Data and information from Ministry of Health (2013) showed the coverage of exclusive breastfeeding 0-6 months according to the province, exclusive breastfeeding in South Kalimantan amounted to 58.7%. Based on the results of a preliminary survey in the Loktabat Utara Village exclusive breastfeeding coverage is only 43%. Low coverage of exclusive breastfeeding was caused by working status of the mothers where the demands of the job so that less time is available to provide breast milk to their babies. The purpose of this study is to explain the relationship between knowledge and attitude of working mothers with exclusively breastfeeding practice. This research is quantitative with cross sectional approach. Data were analyzed by univariate and bivariate using ch-square test. Results showed there was no correlation between knowledge (p=0.597) and attitude (p=0.572) of working mothers with exclusive breastfeeding practice. Expected to government, policy makers and health sector further enhance efforts to improve the coverage exclusive breastfeeding through counselling directly to the target audience and provide breastfeeding rooms in the workplace. It is also necessary motivation from the family and the people around to nursing mothers for increase exclusive breastfeeding practice.