The aim of this study was to determine relations between cambial activity and flavan contents on hazelnut. While cambial activity were followed on cross sections between 14 February and 13 September, flavan contents were detected in phloem tissues of annual shoots between same dates. According to results, cambium under ecological conditions of Van province activated in mid April, summer wood started to form in the second half of June, cambial activity finished at the beginning of October. The level of flavans were lower in fast growing period, and higher towards ends of vegetation period. There was a positive relation between cambial activity and flavan contents.