Wireless sensor networks are a novel generation of networks consisting of several sensors deployed across a specified region. These nodes communicate with each other in wireless manner. Sensor nodes were expensive in earlier years but as result of growing wireless technology and decreasing cost of sensors, such networks are applied more and more nowadays. These networks have been employed in many application areas and might extend to various other fileds also. Nevertheless, environment monitoring and target tracking are two major applications of these networks. Having many areas of usage, researchers have been focusing on problems and concerns of these networks lately. To develop wireless sensor networks, some challenges have to be resolved. There’s a challenging issue in design of protocol stack layers specifically for these networks. One of those layers is traort layer which plays an important role in reliable end to end delivery over IP networks. This role has a key functionality in some applications of wireless networks, especially for those ones controlling and responding an event happening through network region. They are called control and action applications sometimes. In such applications, data transmission from sensor nodes to base station (sink) is important. Traditional solutions for traort have not paid attention to event traort problem sufficiently; that is to say transferring quantitative characteristics is not taken into account suitably. This is a real necessity in some applications. Delivering the information of an event is volnurable due to packet loss. So in this thesis a traort scheme is proposed to transfer data from sensor nodes to sink called event-to-sink traort. This scheme is based on clustering and divides the whole network into regions. Each region has some special nodes called head-node in charge of aggregating and transmitting data packets to the sink. On the other hand according to the application specific criteria, the sink determines whether or not reliable traort is carried out. If reliability did not meet, the sink tries to recover packets of the event. These retries will be repeated until a specified iteration reaches to a threshold, and then the sink ignores more retrying. Moreover, since the design of the algorithm is parametric, one can change the variables flexibly. Simulations were performed in OPNET tool version 14.5 and results showed that the proposed algorithm can easily traort events from a region to the sink. The results were compared with the case the traort algorithm were not executed. It means t Keywords: wireless sensor network, reliable traort, reliability, event-based.