Diazepam injection was subjected to different stress conditions, as prescribed in ICH guidelines with an emphasis to both pristine drug as well as final formulation. The degradation of diazepam was found to occur mainly in hydrolytic and to some extent in photolytic conditions, while the drug was stable to oxidative and thermal stress. The drug was particularly labile under neutral and alkaline hydrolytic conditions. Diazepam sample was exposed to accelerated, thermal and photodegradation conditions as observed during hot and humid summer conditions in Indian subcontinent as per ICH guidelines. The samples were analyzed by a validated high performance liquid chromatographic method. Results obtained confirmed the photo and hydrolytic labile nature of diazepam. Thus, an appropriate protection is recommended during storage and handling of this tranquilizer such that the assay, purity and potency of the drug is maintained.