Nurses provide the bulk of primary care services in South Africa. Post-apartheid health legislation envisions the provision of comprehensive primary services at all public clinics, which implies the need for a cadre of primary care nurses able to render such services. To identify core competencies of clinic nurses and develop an evaluation tool for primary care nursing in South Africa. The descriptive and exploratory techniques used included two meetings of a reference group of South African primary care professionals, followed by a consensus-building exercise. Using the Delphi technique expert opinion was solicited from South Africa, Canada and the USA. The reference group meetings yielded a list of nine core competencies. Infrastructure issues, such as the supermarket (one-stop shopping) approach to service delivery, communication and transport systems, and the quality of supervision still cause concern. These issues underscore that competence cannot be measured in a vacuum. Input from Delphi participants affirmed the nine core competencies and the need to assess the impact of core competency training. One possible way to measure the nine core competencies would be to use proxy indicators. Identifying core competencies is a complex process. There is a need to process a wide range of views and ideas. Also, balancing academic concerns with service delivery needs and constraints is an ongoing challenge. A potential limitation of the Delphi technique is participant selection bias and fatigue. Accessing a diverse international panel and making numerous follow up attempts via phone, mail and email were used to attempt to ameliorate these inherent limitations. Although the process is cumbersome, providing "experts" with a venue to wrestle with these ideas can be fruitful. Future studies would help to assess the reliability of the findings.