Needle retention in conifers is affected by several environmental factors, e.g. climate, mineral nutrition, other edaphic conditions, and more recently by air pollution. This paper describes a method to determine the history of needle retention in pine stems. In the pines so far investigated, the retention of needles varied from one to four annual needle sets (year classes); and there were significant differences in the variation of retention between individual trees. No descending trend was detected which could have been caused by adverse changes in the environment. Some years with deep troughs in the retention data could be connected with exceptionally cold vegetative periods.