This chapter presents a comprehensive review of near-infrared spectrometry (NIRS) and related methods, implemented in brain-computer interfaces (BCI). Basic physical principles of such devices are described. Reviews supply readers with summary of recent development in dynamics and perspectives of the field in question. Examples of NIRS usage in BCI systems are provided and different experimental paradigms are described. Review not only deals mainly with noninvasive NIRS-BCIs but also covers some instances of usage of neighboring fields methods (such as EEG, for instance) for the sake of their importance in so-called hybrid BCI systems and/or in fundamental research, which may be less relevant in case of separate application of different encephalographic methods. As potentially beneficial for NIRS-BCIs, the phenomena of fast optical signals (FOS) are described, and some research on connectivity, including those based on NIRS, is covered. Some attention is paid to the perspective for future BCI's construction using optogenetics.