The formulation development for poorly soluble drugs still remains a challenge. Supersaturating drug delivery systems (SDDS) or drug delivery systems based on supersaturating provide a promising way to improve the oral bioavailability of poorly water-soluble drugs. In supersaturable formulations, drug concentration exceeds the equilibrium solubility when exposed to gastrointestinal fluids, and the supersaturation state is maintained long enough to be absorbed, resulting in compromised bioavailability. In this article, the mechanism of generating and maintaining supersaturation and the evaluation methods of supersaturation assays are discussed. Recent advances in different drug delivery systems based on supersaturating are the focus and are discussed in detail.This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.