We studied four groups of one hundred patients older than forty years. A group with radiological signs of cervical arthrosis was statistically compared with another one without such signs. There was no significant difference between the two groups with regard to the presence of vertebrobasilar insufficiency. Then we compared one hundred patients diagnosed of vertebrobasilar insufficiency with another group without this disease. When cervical arthrosis cases in these two groups were statistically compared, we could not find any significant differences. We think cervical arthrosis is not an important etiologic factor in vertebrobasilar insufficiency. Our results point to atherosclerotic lesions as the main cause of this entity.