During routine EEG recording several incidentally found cases of synchronisation of the basic EEG rhythm with respiratory activity were revealed. EEG synchronisation with the vagal activity has been discussed in several papers and the presented observation shows how intensively such phenomenon can manifest in some cases. The studied phenomenon cannot be univocally interpreted because of the indeterminate mechanism of its origin. Some possible casual factors are also discussed.

        Key words: autonomous nervous system, electroencephalogram, yogism, K-complexes, respiratory arrhythmia