Studies on the behavior of Anopheles darlingi were conducted at a site along the Ituxi River, Amazonas, Brazil. Patterns of host-seeking activity inside and outside a single-walled house both presented activity peaks at sunset and sunrise, but biting activity inside a four-walled house peaked after sunset then gradually decreased during the night. Major movements of females into and out of the four-walled house occurred at sunset and sunrise, respectively. Marked engorged and unengorged females released indoors were observed to preferentially rest on the ceiling. These behavior patterns were confirmed by replication and/or with more than one sampling technique or study method. Additional observations on exit sites, spatial distribution of resting females and physiological condition of exiting specimens were recorded.