This paper develops a new algorithm to improve the security of RC4. Given that RC4 cipher is widely used in the wireless communication and has some weaknesses in the security of RC4 cipher, our idea is based on the combination of the RC4 and the poly alphabetic cipher Vigenère to give a new and more secure algorithm which we called VRC4. In this technique the plain text is encrypted using the classic RC4 cipher then re-encrypt the resulted cipher text using Vigenère cipher to be a more secure cipher text. For simplicity, we have implemented our new algorithm in Java Script taking into consideration two factors: improvement of the security and the time complexity. To show the performance of the new algorithm, we have used the well known network cracking software KisMac.