A ssessing and measuring patient compliance is assuming increasing importance in clinical practice. Noncompliance has been shown to be a common cause of relapse in many conditions, for example, in bipolar patients on lithium (1), depressed subjects on antidepressants (2), schizophrenia patients on neuroleptics (3,4), and nephrology patients who have received a kidney transplant (5). It has been found that around 50% ofgeneral medical patients (6), 50% ofpsychiatric patients (3), and an average of 33% of hemodialysis pa- tients (7) fail to comply with the basic requirements of the treatment regimen.Compliance is commonly assessed by asking the patient whether he or she is following the prescribed treatment plan. However, for various reasons patient reports are often unreliable. With reference to medication compliance, reliability is improved by counting pills left over after prescribing known quantities of drugs or by talking to friends and nextofkin. Various electronic devices are available to monitor medication-taking (8). Where feasible, biological measures are used to confirm or corroborate clinical evaluations (9).This latter study noted that clinical ratings tended to beinaccurate and overestimated the degree of compliance in 50% of patients. In dialysis patients, however, nurses' ratings of compliance have been found to be valid and reliable (10). Conversely, biological ratings are intrusive, expensive, and cumbersome, and in the case of psychiatric populations, blood levels of neuroleptics and most antidepressants correlate poorly with clinical effectiveness. A clinical ratingthat was easy to administer, combined subjective report withbehavioural evaluation, and was reliable and valid would be valuable and time-saving in clinical practice. It would also