Membrane proteins (MPs) play key roles in most crucial cellular processes ranging from cell to cell communication to signaling processes. Despite recent improvements, the expression of functionally folded membrane proteins in sufficient amounts for their functional and structural characterization remains a challenge. Indeed, it is still difficult to predict whether a protein can be overproduced in a functional state in some expression system(s). Prokaryotic expression systems present several advantages over eukaryotic ones. Among them, Lactococcus lactis (L. lactis) has emerged in the last two decades as a good alternative expression system to E. coli. The purpose of this presentation is to describe L. lactis and its tightly inducible system, NICE, for the effective expression of membrane proteins from both prokaryotic and eukaryotic origins.