This review is about the α-Lactalbumin (α-LA), the major whey protein found in the milk of all mammals. It is a simple Ca2+ binding milk protein, homologous in sequence to the lysozyme family and has significant role in biosynthesis of lactose in the lactating mammary gland. The structural and functional analyses so far obtained about this protein were outlined here. As regards the structure, it displays the best-characterized molten globule state which has been studied by various techniques such as X-ray scattering, NMR, thermodynamic study, ultrasonic study etc. The functional aspect shows many remarkable features of its calcium binding sites and is found to be a valuable constituent to enrich the infant formula. In addition, α-LA can alter its biological function depending on the conformational state and actively interact with lipid membranes, which leads to its antimicrobial and antitumor activity that has a vital role to induce apoptosis in tumor cells. Recently it was found that fabrication of α-LA nanoparticles to use in drug and food delivery system in nanomedicine is also possible.