This paper highlights the importance of team influence in affecting professionals’ acceptance of large-scale information systems. A longitudinal study involving 103 physicians was conducted with two data collections performed three months apart. The results show that team influence has a significant effect on perceived usefulness, but not on perceived ease of use, and that satisfaction with using the system of interest is significantly affected by team influence, but not by perceived usefulness. The findings make contributions to both research and practice of information systems.