The compliance of patients with medication prescribed for them is a challenge. It seems that one-third of patients comply adequately, one-third more-or-less, and one-third are non-compliant, so that compliance rates hover around 50%. This can be improved upon, but not by treating failure to comply as a deplorably aberrant behaviour. First we need to know more about compliance and non-compliance, and that means standardising methods of study and measuring, by questioning the patient, counting tablets, or looking at drug metabolites or markers in faeces, blood or urine. Doctors' prejudices and patients' perceptions alike have to be taken into account since strategies for improvement must include both educating the prescriber and counselling the patient.