A sensitive and selective liquid chromatography tandem mass spectrometric (LC-MS/MS) analytical method has been validated to quantify manidipine in human plasma using desipramine as an internal standard (IS). Liquid-liquid extraction (LLE) with a mixture of methyl-t-butyl ether and hexane (4:1, v/v) was used for sample preparation. The separation of analytes and internal standard was performed on a C18 column (3 mm x 50 .mm, particle size 2.5 m) with gradient elution of (A) 0.05% formic acid and (B) acetonitrile. The mass spectrometry method was performed employing positive electrospray ionization (ESI) operating in multiple reaction monitoring (MRM) mode, monitoring the transitions of m/z 610.98 > 166.95 for manidipine and m/z 266.95 > 235.94 for the IS. The total analytical run time was 6 min. The calibration curve was linear over manidipine concentrations ranging from 0.1 ng/mL to 20 ng/mL in plasma with a correlation coefficient (r2) of 0.995 or better. The lower limit of quantification (LLOQ) and limit of detection (LOD) for manidipine were 0.1 ng/mL and 0.0125 ng/mL, respectively. Accuracy and precision were within the acceptance criteria of the United States (US) Food and Drug Administration (FDA) guidelines. The rapid and highly sensitive LC-MS/MS method has been developed and successfully applied to a bioequivalence study of manidipine in Thai healthy volunteers after oral administration.