Preparation of electrochemically treated pencil graphite (ETPG) electrode and its application for the determination of DA in the presence of ascorbic (AA) and uric (UA) acids were investigated. Several important parameters were worked to control the performance of the ETPG electrode which showed a high selectivity and sensitivity toward DA. A linear relationship was obtained for dopamine (DA) over the concentration range of 0.01 and 5.0 mu M with a detection limit of 0.31 nM in the presence of AA and UA. The fabrication reproducibility of the ETPG electrodes (n = 10) showed an acceptable reproducibility with a RSD of 2.0% for 5.0 mu M DA. The determination of DA in blood serum without any pretreatment and dilution has been reported for the first time in this work.