This study reviews the principles and practice of neuromarketing. Recently, the field of market research has adopted and benefited from the dramatic developments of neuroscience. Neuromarketing, which combines marketing with neuroscience, is now considered to be a valuable research tool complementing other behavioral research methodologies being used for marketing research. Unlike the existing consumer research methodologies, such as survey and interviews, which primarily consumer decision making above conscious level, neuromarketing, when harnessed properly, is expected to provide key information into the consumer ‘black box.’ Various neuroimaging techniques, such as fMRI(Functional Magnetic Resonance Imaging), and PET(Positron Emission Tomography), as well as EEG(Electroencephalography), MEG (Magnetoencephalography), and Eye-tracking System are available for the use of neuromarketing. Major companies in Korea and the US have used neuromarketing to improve their marketing strategies. We introduce two Korean cases and two US cases as pioneer neuromarketing cases. Amorepacific gained confidence in new color make-up product lines after investigating initial consumer responses which appeared on fMRI. Kia Motors successfully launched a new automobile brand called K-7 after they received an auspicious signal from their neuromarketing research. US consumers' brain activations responding to Coca Cola vs Pepsi showed a clear distinction of brand preference. Viewer responses to outstanding ads at the Super Bowl included the activations of mirror neurons. In addition, neuromarketing can provide useful marketing intelligence in venues such as product concept testing, market opportunity analysis, competition analysis, brand naming, pricing, packaging decision, and advertisement copy-testing. Challenges of neuromarketing include technical complexity as well as high costs of using neuroimaging facilities. Since neuromarketing can tap into the subconscious and implicit consumer decision- making, it is necessary for researchers pay due attention to the potential ethical problems and privacy issues associated with the use of neuromarketing.