A lectin with the potent mitogenic and in vitro anti-proliferative activity has been purified from tubers of a wild monocot plant Arisaema utile Schott by affinity chromatography on asialofetuin linked amino-activated silica beads. Arisaema utile lectin (AUL) gave a single band in SDS-PAGE at pH 8.3 corresponding to subunit Mr 13.5 kDa. The native molecular mass as determined by gel filtration chromatography was 54 kDa, suggesting a homotetrameric structure. Like other monocot lectins, AUL gave multiple bands in isoelectric focusing and in native PAGE at pH 8.3. AUL was inhibited by N-acetyl-D-lactosamine (LacNAc), a disaccharide and asialofetuin, a complex desialylated serum glycoprotein. When treated with denaturing agents, the lectin was stable in the presence of urea (3 M), thiourea (4 M) and guanidine HCl (4 M). The lectin had no requirement for divalent metal ions i.e. Ca2+ and Mn2+for its activity. AUL was a glycoprotein with a carbohydrate content of 1.2%. Amino acid analysis revealed high content of aspartic acid, glutamic acid, glycine and threonine and a very low amount of methionine but complete absence of cysteine. Amino acid modification studies of AUL revealed tryptophan and tyrosine residues involved in lectin-sugar interaction. The lectin showed potent mitogenic response towards human lymphocytes. The mitogenic activity of AUL was even more than that of Con A, a standard well-known plant mitogen. AUL exhibited a fluorescence emission maximum (λmax) at 340 nm upon excitation at 295 nm. Using Far UV CD spectra the estimated secondary structure was 37% α-helix, 25% β-sheet and 38% random contributions. In vitro anti-proliferative activity of AUL was tested on eleven different human cancer cell lines viz. MCF-7 (Breast), SK-N-SH (CNS), 502713 (Colon), Colo-205 (Colon), HCT-15 (Colon), HT-29 (Colon), SW-620 (Colon), Hep-2 (Liver), IMR-32 (Neuroblastoma), DU-145 (Prostate) and PC-3 (Prostate). The concentrations of AUL which produced 50% inhibition (IC50) of cancer cell lines viz. SW-620, HCT-15, SK-N-SH, IMR-32, Colo-205 and HT-29 at 38, 42, 43, 49, 50 and 89 µg/ml. respectively. AUL was found specific for LacNAc in the present study, which is reported as one of the very important cancer marker. Future investigations are focused to exploit lectins using appropriate animal models of human diseases and other agents (e.g., synthetic compounds) to reveal the synergistic effect of these agents to prevent cancer and make a better prediction to which type of protocol, the anti-proliferative effect of plant lectins is most likely to be successful.