The ExacTech system, a new device for home measurement of blood glucose was tested in the laboratory, in the out-patient clinic, and by diabetic patients. The system is based on an electrochemical principle, and consists of specially impregnated strips and a small, pencil-shaped meter. (1) Six meters were tested in the laboratory at blood glucose concentrations of 4, 10 and 20 mmol/l. Low coefficients of variation were found at 10 and 20 mmol/l, but those at 4 mmol/l were rather high (approximately 10%). Analysis of variances showed no difference in the between and the within variation of the meters. (2) The blood glucose concentrations of 50 consecutive out-patients were determined by the ExacTech system and a standard laboratory method. Correlation analysis showed an r value of 0.95 (P less than 0.001). (3) The results obtained by 13 patients repeating the correlation experiment were in agreement with the second part of the study. The ExacTech system is very simple to operate by the patients, and can be recommended for home monitoring of blood glucose.