Ocimum Tenuiflorum locally known as “Tulsi” is a widely used indigenous remedy to several ailments in our households. We have studied the evolution of chlorophyll content in the leafs of this plant over time in a day. We observe that the chlorophyll content reaches it maximum during noon time. This suggests that the leaf extract may be of higher medicinal value when extracted during the noon time. This also provides a scientific explanation to the age old practice in our homes of not using the Tulsi leafs for any purpose after sunset.