In recent years, hospitals in Victoria have initiated a program of adopting various forms of inter-organisational systems (IOS) which link them with their pharmaceutical suppliers. In this paper, we use a positivist multiple case study approach to examine the IOS adoption experiences of three large hospitals, and explain their IOS adoption processes using a theoretical model which we developed based on the ideas of ‘organisational motivations’ for IOS adoption. The findings obtained from the hospitals offer insights about what influences IOS adoption processes in organisations, which in turn, help in reducing the uncertainty associated with IOS adoption practices.