The third CMR Workshop prov. ided the opportunity for a group of experts from the Industry, academia and the regulatory authorities to meet and discuss ways and means by which risk benefit decisions are made during the various stages of drug development. It became apparent from the discussions that took place in October 1985, at the CIBA Foundation, that decisions are often made with limited data and inadequate methodology. The conclusions drawn from the day's deliberations were as follows: 1. Current methodology for assessing risk and particularly benefits must be improved; 2. Safety must be assessed in association with benefits as it is ultimately the benefit/ risk ratio which should decide the future of medicines; 3. Risks from medicines must always be viewed in relation to the risks from untreated diseases. It seemed to be the consensus of the group that such a meeting was both useful and informative and, hopefully, the publication of these proceedings will stimulate further discussion in this important area which may improve the decision-making process in drug development. The Editors wish to thank the participants for contributing to the Work shop, together with Dr. Cyndy Lumley for providing the initial transcript of the meeting and Mrs Sheila Wright for producing the final version and for carrying out all the additional work that is entailed in producing such a publication. Professor S. R. Walker A. W."