There were still many nurses who have not implemented in accordance with SOP standards and there were still many acts of nurses who were not disciplined when doing work, especially when weighing can affect the performance of the nurses themselves, so that the nursing services provided would be disrupted. This study aimed to determine the relationship between work discipline and the performance of nurses in the implementation of weigh-in at Prof. Hospital. Dr. Soekandar Mojosari. This research design used correlation analytic with cross sectional approach. The population in this study were all nurses at Prof. Hospital. Dr. Soekandar Mojosari as many as 245 nurses. The sampling technique of this research was simple random sampling. The sample in this study as many as 71 people. The research instrument used a questionnaire. Data analysis using Spearman Rho test. The results suggested that most of the respondents had good work discipline, as many as 47 people (66.2%) and almost all of them had good performance in the implementation of weighing, as many as 58 people (81.7%). The results of the Spearman Rho test suggested that p-value = 0.000 < = 0.05 with a correlation coefficient of 0.663, which meant that there was a strong relationship between work discipline and nurse performance in the implementation of weigh-in at Prof. Hospital. Dr. Soekandar Mojosari Mojokerto. Respondents who have good work discipline, their performance will be fulfilled completely because respondents understand the work rules and their responsibilities in weighing and accepting so that they will do according to the rules made by the hospital.