This text book describes the analysis on end-to-end delay for wireless sensor network using multi path routing protocols. The analysis on end to end delay refers to the total time taken for a single packet to be transmitted across a network from source to destination. It is one of the most important and fundamental issue for wireless sensor networks. A novel multi path routing protocol based on ant colony optimal (ACO) has been explained with suitable algorithm and examples. MRP improves the efficiency of data aggregation, thus, reducing the energy consumption. An improved ACO algorithm can be used to search for the optimal and sub optimal paths based on many metrics, which can balance the energy consumption among nodes. Furthermore, a load balancing function is presented for dynamically choosing one path to transmit data. This text book covers basics, multi path routing techniques and analysis on end to end delay in WSN and will be very much useful for the students and scholars who are interested in the research area of Wireless Sensor Networks.