A decentralized detection system operating in asynchronous mode is presented. The local sensors generate their decisions asynchronously and convey them to a global decision maker (GDM). A sequential decision fusion scheme is implemented at the GDM in order to reach a global decision. It is assumed that local decisions are generated according to a Poisson process at each local sensor. A performance comparison with the equivalent fixed-sample size test is presented. Truncation of the sequential test is also addressed.