We present a comparative study of monoterpenes in in vitro and field grown plants of Mentha arvensis L. (Japanese mint). Apical and nodal explants were cultured on MS agar-solidified media + BAP (0.2 to 1 mgL-1) for shoot induction. Highest shoot induction was obtained at 1mgL-1 BAP from both explants. The number of shoots was highest at 0.75 mgL-1 Kinetin and 1mgL-1 BAP from axenic shoots. In vitro grown shoots were cultured in ½ MS salts + IBA (2 mgL-1) for rooting. Excellent callus was achieved from leaf explants cultured on MS medium + 2,4-D 3 mgL-1 or 0.25 mgL-1. In vitro, field grown and callus were subjected for extraction and evaluation of monoterpenes. There were 17 constituents detected from field grown plants by Gas Chromatography- Mass Spectrometery (GC-MS) of which menthol was the major component (57.44%) as compared to menthone (9.17%) and pulegone (7.73%), whereas, menthone with 65.32% was the main component of oil extracted from 16 weeks old calli followed by menthol (0.11%) and pulegone (0.21%). Mint oil extracted from in vitro plants showed variable concentration of 15 different compounds.