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Mammillaria pectinifera, is a rare cactus of central Mexico currently threatened by extinction due to its restricted geographical range, high habitat specificity, relatively low growth rate, and small population sizes. In this paper, we analyse its demographic performance over a 1-year period using survival, growth and reproduction data. We carried Out a demographic analysis through a Lefkovitch size-based matrix model. As this cactus shows long-term fruit retention in the stern, we included the seed stage explicitly ill our analyses. The matrix analysis revealed that the estimated population growth rate (lambda) is 0.743 Suggesting a declining population with limited persistence ability. Juvenile and adult Stages showed higher elasticity values than the other stages: however our matrix simulations resulted in a Positive population growth rate only when fecundity entries and seedling establishment Success were increased simultaneously. We suggest that any management plan aiming at the preservation of M. pectinfera should consider specific programs to enhance seedling establishment and adult survival. (c) 2005 Elsevier Ltd. All rights reserved.