The present invention relates to stable transdermal pharmaceutical drug delivery system of diclofenac or a pharmaceutically acceptable salt thereof. In particular, the present invention relates to stable transdermal pharmaceutical drug delivery system of diclofenac or a pharmaceutically acceptable salt thereof free of any penetration enhancer and/or an antioxidant. More particularly, the present invention relates to stable transdermal pharmaceutical drug delivery system of diclofenac or a pharmaceutically acceptable salt thereof provides an enhanced absorption of drug through skin, flexible backing, longer duration of action, and inhibits crystal formation of drug substance during storage period.
