The recent development in wireless technology has made remarkable enhancement in productivity in the corporate and industrials sectors. However, these developments also introduced new security threats. Wormhole attack is one of the most security threats in wireless networks. An experimental investigation was conducted to explore the impact of the Wormhole attack particularly on mobile ad hoc networks. By using the AODV routing protocol, the differences between with and without attack situation is investigated by a numerical study. The results reveal that the attack gives a big impact on reduces Throughput, increase both delays, and Normalized Routing Load. The results presented here may facilitate improvements in the detection issue, prevention issue, and optimization of the network performance later