Investment on Enterprise Resource Planning (ERP) systems has increasing trend in Pakistani organizations. Acceptance of entirely new technological system such as an ERP seems very critical in these organizations. In this study, the acceptance of ERP system was examined with Technology Acceptance Model (TAM) after the addition of user satisfaction dimension. Data was collected through field survey from 211 ERP end users from the public sector service organizations of Pakistan. For testing measurement and path models, partial least squares structural equation modelling (PLS – SEM) technique was applied. Findings indicate the positive and significant impact of user satisfaction on perceived usefulness (PU) and perceived ease of use (PEOU). In the same lines, PU and PEOU has positive influence on intention to use and finally intention to use positively increases the usage of ERP system in these organizations. Based on the findings, some practical implications were also discussed.