The Mouth Dissolving Drug Delivery Systems was an advancement that came into existence in the early 1970’s and combats over the use of the conventional tablets, syrups, capsules which are the other oral drug delivery systems. Orally disintegrating dosage forms can address the pharmaceutical needs of the paediatric and geriatric patient group having difficulties in swallowing the conventional solid oral dosage forms. Orally disintegrating dosage forms also have the advantage of self medication, pain avoidance hence better patient compliance. Taste masking of bitter drugs is an important parameter. Orally disintegrating dosage forms may have an added advantage of bypassing first pass metabolism. Acyclovir is an antiviral drug used for the treatment of herpes simplex virus (HSV), mainly HSV-1 and HSV-2 and varicella zoster virus. It is a BCS class III drug. Hence an orally disintegrating tablet formulation of acyclovir was prepared by direct compression techniques after incorporating superdisintegrants croscarmellose sodium , sodium starch glycolate and Crossprovidone . Eight formulations were prepared. Tablet containing sodium starch glycolate and croscarmellose sodium showed excellent in vitro dispersion time and drug release as compared to other formulation. After   study of eight formulations F8 showed short dispersion time with maximum drug release in 25 min. It is concluded that fast disintegrating acyclovir tablets could be prepared by direct compression using superdisintegrants.