200 patients attending a diabetic outpatient clinic were each asked to post to the hospital, prior to their three-monthly routine clinic visit, a finger-prick capillary blood sample for glycosylated haemoglobin assay (HbA1). Patients took their own blood into UNISTEP bottles, which automatically measure a 53 microliters aliquot and mix it with 150 microliters of diluent suitable for transport to the laboratory. During 1 year 883 (84%) of 1046 bottles sent out were returned of which 776 (87%) were suitable for analysis. The availability of the result at the time of the patients' clinic visit aided assessment of diabetic control and was associated with a mean reduction of the HbA1 by 0.8% (p less than 0.001) over a twelve-month period. This simple system facilitates remote monitoring of HbA1 levels, is suitable for both hospital and general practice use and may allow a reduction in the number of patient visits.