Exit-traps were used to estimate the density of the malaria vector Anopheles aconitus in cattle shelters in five localities near Semarang, Central Java, from Mei 1980 to October 1981. Collections of resting mosquitoes in two cattle shelters by aspirator during the same period were used as a comparison. Results indicate that exit trap, were less productive compared to mosquito collection in cattle shelters using aspirators. However, weekly fluctuations of densities obtained from exit-traps and from cattle shelters are the same pattern and both showed a significantly positive correlations. Most of An. aconitus caught in exit traps are blood fed and very few gravid, these supports the theory that this species is highly exophilic.