This paper introduces a geo-ecological analysis done on a relict, threatened and little known Mediterranean population of yew (Taxus baccata). We study the case of Sierra Arana (southern Spain). The priority is to know under what conditions the species develops and its ability for future preservation, for which, through fieldwork -the main methodological procedure-, its identification and location and the analysis of not only its population demographic structure, but also of its conservation status, its habitats and ecological niches are undertaken. The results obtained are a chorological map of the species and a major knowledge of it; establishing: a) predominance of mature trees -middle-aged and long-lived-, scarcity of young specimens and absence of seedlings; b) a significant imbalance in sex ratio, prevailing male individuals; c) a conservation status that varies from optimum to degraded for the population as a whole; d) habitats located on very steep slopes over basic soils, even in sub-rupicolous locations; e) ecological niche corresponds to preforestal orla of deciduous and marcescent forests of Acer monspessulanum and Quercus faginea. Finally, we present a proposal for the conservation and regeneration of yew based on the protection of existing specimens and on the reforestation in the most appropriate ecological niches. The main conclusion established is the critically endangered state of Taxus baccata in Sierra Arana due to its little chance of natural regeneration and expansion, requiring extraordinary measures to its preservation.