<p><strong>Background:</strong> Knowledge of the flowering phenology of species with an epiphytic habit and a dioecious sexual system is scarce.</p><p><strong>Questions:</strong> We studied the flowering phenology of a population of the dioecious epiphytic bromeliad, Catopsis compacta, in an oak forest in Oaxaca, Mexico, to answer the following questions: 1) what type of flowering period is exhibited by this population of C. compacta? 2) what is the degree of synchrony between the male and

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... e flowering periods? and 3) what is the flowering synchrony index of the population?</p><p><strong>Methods:</strong> In February 2006, in a 20 m × 20 m plot, we marked and measured 151 individuals of C. compacta ≥ 10 cm in height (minimum reproductive size). We recorded the number of flowers and fruits present in each individual every month for one year.</p><p><strong>Results:</strong> Our results showed that the flowering period in both sexes lasted for three months (May–July). Only 23 marked individuals flowered (15.23 %): of these 12 (52.17 %) were female and 11 (47.83 %) were male. The index of synchrony between females and males was 0.958 ± 0.013 and the flowering synchrony index of the population was 0.833 ± 0.189.</p><p><strong>Conclusions:</strong> The high flowering synchrony between the sexes, together with a flowering season that coincided with the period of highest rainfall when the number of arthropods (potential pollinators) is the highest, could favor breeding and, therefore, reproductive success.</p>