The movement of Aedes aegypti (L.) and Aedes albopictus (Skuse) females between sylvatic and urban environments was investigated by marking, releasing, and recapturing adults and by identifying rubidium (Rb)-marked eggs of females that were released after taking a bloodmeal containing RbCl. When released in the forest, Ae. albopictus females ßew as far as 1,000mand reached houses within 1 wk. When Ae. albopictus were released close to houses, most females were recaptured near the release point, and Rb-marked eggs were found 1,000 m away in the forest only once, 35 d after the release. These differing patterns of movement may suggest a preference of Ae. albopictus for the human-modiÞed environment. Ae. aegypti, however, showed low tendency to disperse into the forest. The capacity of Ae. albopictus females to disperse from a sylvatic into a human-modiÞed environment suggests that this species may play a role in the dissemination of forest-restricted pathogens, such as yellow fever virus.