A simple, rapid and selective stability indicating HPLC method has been developed for quantitation of acyclovir in pharmaceutical dosage forms (gel, ointment, cream) using a mobile phase consisting of 5% v/v acetonitrile in 0.01 M Potassium Dihydrogen Phosphate (KH2PO4) acqueous buffer solution (pH = 4.8) at a flow rate of 1.0 ml/min. A Finepak C-18 column was used as stationary phase. Quantitation was performed using uv detector at 255nm. Method showed good resolution between main peak and peaks of degradation products. The method is sensitive, accurate and precise. The excipients present in the dosage form did not interfere with the assay method. The recoveries for acyclovir from dosage forms were quantitative. Acyclovir appears to be more stable in alkaline than acidic media.