Earlier work demonstrated that L-lactate metabolism is associated with serum resistance and survival of Haemophilus influenzae type b in vivo. To gain insight into lactate utilization of non-typeable strains deletion mutants of the L-lactate dehydrogenase(lctD) and permease (lctP) of NTHi 2019 and laboratory strain Rd KW20 were generated and characterized. Comparison of COPD isolate 2019 with the corresponding lctP mutant did not reveal a lactate dependent alteration in serum resistance. Interestingly, we observed a 4-fold attenuation of the mutant strain in a murine model of nasopharyngeal colonization, highlighting a potential role of L-Lactate to persist in this niche. Characterization of lctP transcriptional control shows a negative feedback regulation in the presence of L-lactate, depending on the ArcAB two component system. Additionally, for 2019 it was found that available but not metabolized lactate may have an ArcAB independent signalling function leading to increased cell growth in late log phase. We conclude that L-lactate is not only an important carbon-source but may also act as signal substrate, fine tuning the globally acting ArcAB regulon and potentially a yet unidentified signalling system. Additionally, our data suggest that the ability to take up lactate provides a selective advantage during colonization of the nasopharynx.