Abstract This method has been designed to determine the levels of CoQ 10 in human blood which utilizes only one drop of blood (0.05 ml). This method encourages and facilitates more frequent monitoring of blood levels of CoQ 10, and of clinical importance, reveals the presence or absence of compliance. CoQ 11 was used as an internal standard. The mean recovery of CoQ 10 was 96%. The correlation coefficient between using 1.0 ml and 0.1 ml of blood and between using 1.0 and 0.05 ml was 0.997 in the two comparisons. Therefore, it can be accurate to monitor the level of CoQ 10 in a-"finger-prick"-drop of blood, and at least 24 such determinations can be conducted in a 2-day period.