Abstract: Thirty thousand and fifty-two newly emerged adults of Anopheles dirus marked with metallic dust were released in a valley of mountainous area in Hainan Island. Totally 0.472% of marked females were recaptured by man bait in four successive nights after release. The dispersal numbers of recaptured females in all directions were insignificantly different and reached one kilometer, but the furthermost was 1.4 kilometers to the south of releasing point.