Osmoregulated drugdelivery systems(ODDS)are unique solid dosage forms, just like any tablet, that deliver drug as solution from anorifice following zero order kinetics. They are also called as Osmotic Pump. ODDS are of many types, like elementary osmotic pump, pushpull, controlled porosity, gastroretentive and colon targeted osmotic pump and osmo matrix tablets. In general it has a drug and osmotic core, a convex shaped tablet, coated with a semipermeable membrane and a laser or mechanical drilled orifice on oneside of the coated tablet. Each osmotic pump has some modification in the formulation. Drug delivery from each ODDS occurs in control led manner, that too as liquid drops, for predetermined prolonged periods of time. Formulation aspect and mechanisms of drug delivery from each ODDS will be discussed during the presentation.