Objectives: To compare the phyto-chemical and physico-chemcial differences between green leaves monotype (MT1) and purple leaves monotypes (MT2) of Ocimum sanctum Linn grown in selected provinces of Sri Lanka. Methods: Essential oil was extracted by hydro-distillation using Clevenger type apparatus and analyzed by Gas Chromatography technique. Physico-chemical investigations were done according to WHO guidelines. Results: Highest amount of essential oil content was present for both MT1 and MT2 of O. sanctum collected from Southern Province. Moreover, methyl eugenol was present in O. sanctum in a range of 0.2 – 66% and compared to the MT1 methyl eugenol content was higher in MT2 of O. sanctum collected from all selected provinces. The highest percentage of eugenol was contained in MT2 of O. sanctum and there is no significant dependency of the location. Further, it is very interesting to note that percentages of germacrene- D and β-elemene were both higher in MT2 of O. sanctum in WP and SP respectively. However, there was no significant difference in terms of total ash or water soluble ash or acid insoluble ash between MT1 and MT2 collected from four provinces of Sri Lanka. Conclusion: Overall results revealed that MT2 of O. sanctum collected from SP is more versatile in terms of oil content and chemical constituents.