Female and male plants often differ in reproductive effort and habitat requirements. The aim of this study was to analyze these differences between the sexes and the effect of climate on tree-ring width in European yew (Taxus baccata). The study was conducted in five yew populations in western Poland. Wood samples were taken from 196 trees (98 females and 98 males) and subjected to the standard procedure of dendrochronological dating. Mean tree-ring width was significantly higher in males since about the beginning of sexual maturity. No such relationship was observed in the youngest population, which is the most distant from the current geographic limit for this species. In most of the analyzed populations, width of tree rings in female individuals, in contrast to males, was negatively correlated with high temperatures in August and September in the year prior to the formation of the tree ring, and correlated positively with precipitation in June and July in the current year. The differentiation of tree-ring width between males and females likely began when the yew trees reached sexual maturity, probably because of the assumed greater reproductive effort of females in comparison with males. The lack of difference in the youngest population may result from a short time since the beginning of sexual maturity or from a milder climate in that region. Different reactions of the two sexes to climate indicate that this may affect the range and viability of populations at the limits of the range.