The lactose hydrolysing system of Streptococcus faecalis is described. It is closely related to that one of the group N streptococci as it consists of a β-D-phosphogalactoside galactohydrolase β-Pgal). The uptake of methyl-β-D-thiogalactoside (TMG), lactose, and glucose is maintained by the phosphoenolpyruvate-dependent phosphotransferase system (PTS) but the uptake of galactose is not. The induction time is 6–7 min. Inducers are lactose and galactose but not isopropyl-β-D-galactoside (IPTG) and TMG. In the presence of glucose, mannose, and maltose no induction of β-Pgal occurs but pyruvate and glycerol allow induction. The competitive inhibition of uptake of TMG by glucose suggests inducer exclusion by this sugar. TMG accumulates in the cells exclusively as a derivative.