A HPLC-method was developed for the simultaneous detection of the lipophilic antioxidants ubiquinol-10, ubiquinone-10, ␣-tocopherol, and ␥-tocopherol in plasma macrosamples (100 l) as well as microsamples (10 l) using electrochemical detection with internal standardization (␥-tocotrienol, ubiquinol-9, ubiquinone-9). The use of a mobile phase containing ammonium formate instead of lithium perchlorate as conductivity salt and the use of a PEEK column instead of a steel column improved the reproducibility of the method. The components were separated on a RP C18 column. The detection limits for all components were between 1 and 28 fmol. The within-day precision varied between 3 and 13% for all measured substances. The analytical recovery was between 93 and 109%. The plasma levels from 10 healthy donors were determined in microsamples and macrosamples taken by micropuncture or venous puncture, respectively. A good correlation of the antioxidant levels for both methods strengthened the reliability and the transferability of the results. The present method can be used to assess the role of these antioxidants in diseases associated with oxidative damage in childhood.