Computerised Provider Order Entry (CPOE) systems provide clinicians with the ability to electronically enter hospital orders for laboratory tests and services. CPOE is able to integrate with hospital information systems and provide point of care decision support to users thereby making a potentially significant contribution to the efficiency and effectiveness of care delivery. The evidence of the impact of CPOE systems on pathology services is not extensive and insufficient attention has been paid to their effect on organisational and communication processes. This thesis aimed to investigate the implications of CPOE systems for pathology laboratories, their work processes and relationships with other hospital departments, using comparative examinations to identify the tasks they are involved in and the particular needs the laboratories expect to be filled by the new system. This longitudinal study of a CPOE system was carried out over three years using multiple cases from a hospital pathology service based at a large Sydney teaching hospital. Multi-methods using quantitative and qualitative data were employed to achieve triangulation of data, theory and methods. The findings provide evidence of a significant 14.3% reduction of laboratory turnaround times from 42 to 36 minutes when laboratory data for two months were compared before and after CPOE implementation. The findings also reveal changes in the pattern and organisation of information communication, highlighting transformations in the way that work is planned, negotiated and synchronised. These findings are drawn together in a comprehensive organisational communication framework that is highly relevant for developing a contingent and situational understanding of the impact of CPOE on pathology services.