There is renewed interest in the functional role of oscillatory brain activity in specific frequency bands, investigated in humans through electroencephalography (EEG) and magnetoencephalography (MEG) recordings. In parallel, there is a growing body of research on non-invasive direct stimulation of the human brain via repetitive (rhythmic) transcranial magnetic stimulation (TMS), and on those frequencies that have the strongest behavioural impact. There is, therefore, great potential in combining these two lines of research to foster knowledge on brain rhythms, in addition to potential therapeutic applications of rhythmic brain stimulation. Here, we review findings from this rapidly evolving field linking intrinsic brain oscillations to distinct sensory, motor and cognitive operations. The findings emphasize that brain rhythms are causally implicated in cognitive functions.