Service changes in the accident and emergency service at Manchester Royal Eye Hospital in England resulted in a telephone triage-based referral service for health care professionals. It became clear that this service needed evaluation in order to assure both providers and users of the service that this referral strategy, based on experienced nurse practitioners making decisions about patient priority, was safe and effective. The evaluation was extended to encompass the other area of the service where telephone referrals tend to be directly from patients. A mixed method was used. Information gained within the telephone triage conversation was compared with a final diagnosis through retrospective analysis of secondary data; the documentation of those patients who were not given access to the service initially was followed-up to ensure that this decision was safe and a number of nurses were questioned about telephone information gathering, using partially structured interviews. The study showed that nurse practitioners within the accident and emergency service were able to elicit accurate information from the telephone triage conversation on which to base a decision about patient access in most cases (76% over the whole service). This resulted in the appropriate prioritization of patients. No patient who needed urgent access to the service was denied it. The decisions made to deny urgent appointments to a number of patients were safe in all cases. It appears that one of the problem areas in the gathering of information for prioritization purposes is in the nurses' telephone triage discussions with some, but by no means all, doctors. Some general practitioners seemed unwilling to discuss the patient and give accurate information to a nurse and this is an area which appears to need some further work.