Today's pharmaceutical manufacturers are more accountable for what their products actually deliver, according to Mark Zitter, President of the Zitter Group in the US. While in the past manufacturers sold their products to individual physicians, purchasers are now much more concentrated - for example, health maintenance organisations or pharmacy benefit management companies - and are able to negotiate discounts and play one manufacturer off against another. One trend to emerge in this new environment is a dramatic increase in the number of clinical outcomes studies conducted by pharmaceutical manufacturers. Mark Zitter elaborated on this and other trends at the Congress on Health Outcomes and Accountability [Washington DC, US; December 1994].