In recent times the concept of Pulsatile Drug Delivery systems has been gaining a lot of attention and importance this is due to the fact that they can release and deliver the medication “At the right place at the right time”. They release a rapid dose of medication after a lag period on the basis of a pre-determined pulse. The most significant application of PDDS is where consistent dosing is not required. They are an innovative system of chronopharmacological conduct that work on the circadian rhythm of the body. This article focuses on the study of Pulsatile Drug Delivery Systems their classification, types, advantages, and disadvantages. Keywords: - Chronobiology, chronopharmacolgy, stimulus, circadian rhythm, pre-determined lag period.