Due to ease of administration, versatility, painless and paramount patient compliance oral administration is considered as most satisfactory route for the administration of drug. For drug absorption in oral cavity, sublingual area is most permeable to drugs. The sublingual route bypasses the hepatic first-pass metabolism, which assist greater bioavailability with better patient compliance. Sublingual route is the most suitable now a days because people need effective relief within a short period. These tablets have the advantage of rapid disintegration and dissolution in saliva. For the instant drug delivery to paediatric and geriatric patients fast disintegrating sublingual tablets have shown significant improvements for specific patient group. This review enlightens the mechanism of sublingual absorption, physicochemical properties of a few sublingually administered drugs, factors affecting sublingual absorption, advantages, and evaluation parameters.