Using data gathered from a mixture of quantitative and qualitative tools, this research into the purchasing of health services, namely occupational health services, is utilized to build an understanding of the role of service professionals in the purchasing of health services. In analysing the themes emerging from the interviews it was found that, typical of a complex, highly intangible professional service, the buyers found it difficult to objectively evaluate the service. The purchasing of occupational health services, similar to other professional services, was perceived to be an uncertain and risky process. The high uncertainties and risk of purchasing occupational health services lead to the utilization of the expertise of the service providers as a risk-reducing mechanism. This understanding of the role of health professionals in the purchasing of health services illustrates that the service characteristics enables the health professionals to utilize their expertise in influencing all stages of this process. © Health Services Management Centre 2004.