The simple, accurate, precise, sensitive, specific and cost- effective UV-VIS Spectrophotometric method was developed for the estimation of acyclovir in bulk and pharmaceutical dosage form, used as an antiviral drug. The absorption maxima of the drug were found to be 252.6nm. in 0.1N H2SO4solvent. The method was validated as per the ICH Guidelines. A linear response was observed in the range of 2-10µg/ml with a regression coefficient of 0.999. The developed method was precise; the % RSD was found to be less than 2%. The LOD & LOQ were found to be 2.3 and 7.0µg/ml respectively. The standard drug was subjected to acidic, alkaline, oxidative, thermal & photolytic stress degradation conditions. The samples so generated were used for degradation studies using the stability indicating UV-Visible Spectrophotometric method. This method was used for the determination of Acyclovir in tablet and cream formulation without interferences of the excipients, this indicated specificity of method.