This paper looks at aspects of doctor-patient communication and focuses on how prescribing decisions fit into the consultation within the context of the use (and non-use) of a technological clinical decision support system (CDSS) in the UK. Analysis of 6 simulated consultations filmed as part of the evaluation of a CDSS system indicated that the general practitioners (GPs) used their computers for a short time during consultations. The data showed that doctors' utterances, occurring at an early stage of the consultations, signalled the prescribing decision and eventual outcome of the consultation. The concept of 'verbal prescriptions' is used to describe these utterances of the GPs, and facilitates an understanding of how prescribing decisions are routinely achieved. Prescribing decisions can occur in the relatively early stages of the consultation, and both prior to and independently of the CDSS. Consequently, we suggest that the pattern of GP decision-making needs to be taken into account in CDSS design. However, this is not just an issue for CDSS design and implementation, as the verbal prescription phenomenon may impact upon patient involvement in decision-making, and even the appropriate use of evidence based medicine.