To a suckling young animal, milk not only provides nutrients but also a myriad of molecules that prime the neonatal mucosal immune system against bacterial infection (e.g. lysozyme, lactoperoxidase, lactoferrin and immunoglobulins). In this study, the presence of human multimeric alpha lactalbumin (HuMAL) was investigated in an animal source, i.e. buffalo milk. Fresh buffalo milk was processed through a series of salt and isoelectric precipitation steps to obtain the crude lactalbumin fraction, which was then further purified by pooling the 280-nm peak obtained after Sephadex G-50 gel chromatography. Only 9.7 mg of buffalo alpha-lactalbumin (BAL) per liter fresh milk was recovered after the isolation series. BAL has been shown to possess a molecular weight of 15 kOA as determined by SOS-PAGE electrophoresis with silver stain. All SkBr3 breast carcinoma cells were killed at 8.0 mg/ml concentration of BAL, while A549 lung adenocarcinoma is refractory to the treatment. This, however, contrasts with the broad-spectrum toxicity demonstrated by HuMAL during a parallel treatment. The mechanism by which BAL exerts its anti-tumor activity towards breast tumors is presumed to be via a combination of early necrosis through loss of plasma membrane integrity within 8 hr post-treatment and largely through apoptosis (programmed cell death) as revealed by Terminal d-UTP Nick End Labeling (TUNEL) with FITC-labeled nucleotides. These findings raise the possibility of prospecting for potential anti-cancer agents from dairy products, as well as, in promoting cancer preventive measures by increasing dietary consumption of fresh milk.