The treatment of aqueous solutions containing various pesticides by cyclodextrin-functionalized mesoporous silica adsorbents was investigated. The pesticides studied belonged to three chemical structure classes: hexachlorocyclohexane-based, hexachlorobicycloheptene-based, and p,p' substituted biphenyl-based pesticides. The solutions studied contained a mass concentration with respect to each pesticide in the range of 0.060-0.270 microg/mL, values that are consistentwith the low levels typically encountered in environmental samples. Adsorbents containing low to intermediate amounts of cyclodextrin groups were found to have optimal adsorption affinity toward the pesticides. The materials were particularly specific toward p,p'substituted diphenyl-based pesticides such as DDT and DDE.