The effectiveness of 2 formulations of deet was tested in the Philippines against Aedes albopictus. A new military issue extended duration repellent formulation (EDRF) was compared with the older standard liquid formulation. Consistently fewer mosquitoes landed on subjects treated with the EDRF than on those treated with the liquid formulation for up to 12 h post-application. However, the difference between the 2 formulations was not statistically significant. Both treatments were significantly different from untreated control subjects. The same was true when other day-biting mosquitoes including Armigeres subalbatus, Ar. flavus and Ae. vexans were analyzed as a group.