Wireless Sensor Networks (WSNs) can be typically used to achieve continuous monitoring or event-detection inside the supervised area. Event detection is a central component in numerous Wireless Sensor Network (WSN) applications. Accurate event detection as well as reliable and real time transmission is basic needs of a good WSNs. This paper describes a survey on event detection and event transmission protocols in wireless sensor networks. Classification of protocols are based on mainly two types i.e. sink centric event detection and transmission protocols and node centric event detection and transmission protocols.