We undertook a two-round Delphi study of the views of consultant geriatricians in three Health Regions on the relative appropriateness of 12 possible performance measures for geriatric services. We compared geriatricians' responses with those of 44 cognitively-intact day hospital patients. Of 138 geriatricians, 89 responded to the first round postal survey, 84 to the second round. The rank order of geriatricians' suggestions did not change from round one to round two, and there was convergence of opinion with a significant decrease in the coefficients of variation of the ranks (p < 0.05, Wilcoxon Test). Geriatricians and patients gave high priority to 'reducing disability' and 'improving quality of life', and low priority to 'reducing mortality'. Geriatricians gave higher priority than patients to 'consumer satisfaction', 'problem resolution' and 'efficient use of resources'. Patients gave higher priority to 'reducing burden on carers', 'measures of service activity' and 'avoiding institutional care'. The study shows that it is possible to obtain a consensus amongst geriatricians about the priorities for measuring the performance of geriatric medical services. Similarities to and differences from patients' views illustrate the need to engage more than one group in the debate about appropriate measures of performance. Findings in both groups give support to recent attempts to develop and use assessment methods for the measurement of disability and quality of life in clinical practice.