In this study, we investigated inter-individual differences in sensitivity to mono-sodium glutamate (MSG) and elucidated the familiarity to umami taste in two European populations. The study consisted of two parts: (1) a survey based on questionnaire and (2) psychophysical screening for inter-individual variation of MSG sensitivity. The psychophysical tests revealed that 3.2% of the German participants and 4.6% of the Norwegian participants were potential non-tasters of MSG. In conclusion, our study confirms inter-individual differences in sensitivity to MSG in humans.