A selective, sensitive, high pressure liquid chromatography-positive electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of aripiprazole in human K2EDTA plasma using zolpidem tartrate as an internal standard. The analyte and internal standard were extracted from human plasma by solid-phase extraction using methanol. The eluted samples were chromatographed on a Grace Smart RP 18 4.6 × 100 mm, 3 µ column by using a 95:5 v/v mixture of methanol and ammonium acetate buffer (30 mM, pH 5.0 ± 0.05) as a gradient mobile phase at a flow rate of 0.6 mL/min, and analyzed by mass spectrometry in the multiple reaction monitoring mode using the M + H+ ions m/z 448.03 → 285.14 for aripiprazole and m/z 308.13 → 235.25 for the internal standard (zolpidem tartrate), respectively. Calibration plots were linear over the concentration range of 0.20 to 60.01 ng/mL. Intra-day and inter-day precision (percent coefficient of variation) and accuracy (percent nominal) for quality control samples (0.60, 30.60 and 45.59 ng/mL) ranged between 2.28 and 8.93% and between 92.50 and 107.07%, respectively. Extraction recovery of aripiprazole from plasma was in the range 75.56-79.57%; mean recovery was 77.35%. The main pharmacokinetic parameters were Tmax = (4.00 ± 2.336) Cmax = (55.16 ± 13.490) and AUC = (1846.28 ± 484.686).