Rhythms at about 10 Hz were recorded from the primary visual cortex of the cat (anterior part of area 18), with characteristics close to those of the alpha rhythm in man: frequency band (7-14 Hz), localization and reactivity to visual stimulation. Coherence analysis of this activity with the "mu" rhythms on the somatosensory cortex showed that although both types develop in the same overall behavioural situations (quiet waking and/or expectancy of an event to occur), they are independent.