Studies have shown that Culex quinquefasciatus oviposits fewer eggs in water treated with Bacillus thuringiensis var. israelensis (Bti). The present study examined the effects of Bti on adults of Anopheles arabiensis. Anopheles arabiensis oviposited in both treated and untreated water with a similar frequency. The number of eggs laid did not significantly differ between the treatments. Adult mosquitoes ingested Bti solution, but it did not significantly shorten their survival time. The neutral effects of Bti on ovipositing An. arabiensis do not reduce its effectiveness as a larvicide for malaria vector control.