© 2020 Asian Pacific Organization for Cancer Prevention.Background: The effect of Aloctin, a lectin purifid from Aloe vera leaves, and aloe emodin an anthraquinone glycoside purifid from the leaves of the same plant, on several cancer cell lines was investigated. Methods: Aloctin was isolated from A. vera leaf skin by ammonium sulphate precipitation and CNBr-Sepharose 4B-ovalbumin affiity chromatography. Specifi new ligands for Aloctin were detected as fetuin and avidin by hemagglutination inhibition tests. The cytotoxic effect of Aloctin and aloe emodin on various human cancer cell lines was tested using MTT assay. Imatinib was tested as standard positive control. The mechanism underlying was tested by the Annexin V-FITC/PI test, with flw cytometry. Results: The most sensitive cells to Aloctin and aloe emodin treatment, were identifid as AGS human gastric adenocarcinoma cells. The effect was concentration dependent. It was shown that this effect does not occur by apoptosis or necrosis. In Aloctin-imatinib combinations studies, Aloctin signifiantly increased the cytotoxic effect of imatinib in a dose-dependent manner. It is expected that the results of this study will reveal important fidings for the future use of A. vera lectin as well as aloe emodin in cancer research and contribution to lectin biochemistry.