ERD/ERS patterns characterize the dynamics of brain oscillations time-locked but not phase-locked to an externally or internally triggered event. Recent studies have shown that ERD/ERS phenomena in narrow frequency bands are remarkably stable over time and across different testing situations. The high reproducibility of ERD/ERS promotes the usefulness of this biometric measure in assessing individual characteristics. In addition to the spatio-temporal patterns of (de)synchronization processes the most reactive frequency components are especially highly subject-specific and, therefore, open up new possibilities for user authentication and person identification. In contrast, ERD/ERS research will continue to be useful in clinical brain-computer interface (BCI) implementation. Promising novel applications of an ERD/ERS based BCI may contribute to enhanced functional recovery and rehabilitation in patients suffering from chronic stroke. According to current therapeutic strategies, feedback-regulated motor imagery could be used to enhance antagonistic ERD/ERS patterns and therewith, support activation of the stroke affected and inhibition of the non-affected, contralesional hemisphere.