Hospital medication errors continue to be a significant problem despite the targeted use of information and communications technology (ICT) interventions. In an ongoing program to add an ‘in silico’ dimension to our multi-method multilevel evaluations we have modelled the significant role of communications in medication error at the context, process and task interaction levels. This extends our previous long-term context and process interaction system dynamics model and adds agent based modeling to more naturally represent the process and task interaction level. The conceptual model integrates previous relevant communications, work and organisational context, task interruption and cognitive overload modeling. The prime focus is to understand and integrate the multiple effects of ICT interventions at multiple levels that can combine to produce unintended results, including new errors. It is being extended to provide a high fidelity systems simulation testbed for designing and testing ICT interventions to reduce medication errors. KEYWORDS: Hospital Medication Error, Communications, ICT, System Dynamics and Agent based modeling