Ultra Fast liquid chromatography – mass spectrometry method (UFLC-MS), for detection and quantification of the anti-tuberculosis drug, ethambutol (EMB), in human plasma is described here. The method uses a single Quadrapole mass spectrometer equipped with positive electrospray ionization detector, linked with Shimadzu 20AD ultrafast LC system. Ethambutol was extracted from human plasma (100 µl) through a single step, simple and straight forward acetonitrile deproteinization method, achieving 98 - 102 % analyte recovery. Short C18 column (50 mm x 2.1 mm) was used with isocratic mobile phase system consisting of 80% aqueous acetonitrile and 0.5% formic acid as additive. Selective ion monitoring (SIM) mode was selected with EMB m/z 205.3 in positive ion mode (MH+). This method achieved wide range of detection from microgram to nanograms of EMB (Linearity R value = 0.9999), with great precision and accuracy. The limits of quantification and detection were achieved upto 19.18 ng/ml and 5.78 ng/ml respectively. This method was applied successfully to determine EMB in plasma samples from TB patients who were receiving EMB along with other anti-TB drugs.