A selective, sensitive, and fast High Performance Liquid Chromatography with mass spectrometric (MS) detection method was developed and validated in human plasma. Nevirapine and Enalapril (internal standard, IS) were extracted from human plasma via solid phase extraction (SPE) technique. After the elution through SPE cartridge, samples were directly analyzed using LC-ESI-MS/MS system. An isocratic mode is used to separate interference peaks using a hypurity advanced C-18, 50 X 4.6 mm ID, 5μ, column. The mobile phase composition was 0.1% formic acid in Milli-Q water (v/v) to acetonitrile at a ratio of 15:85, v/v.The m/z of nevirapine and IS were 267.00 /226.20 and 377.10 /234.10, respectively. Linearity ranges were 10.00 to 5000.50 ng/mL. Calibration functions, lower limit of quantitation (LLOQ), stability, intra- and inter-day reproducibility, accuracy, and recovery are estimated. This method was free from matrix effects and any abnormal ionization. This method was successfully applied to a pharmacokinetic study of nevirapine.