【Objective】 Archidendron clypearia is an important medicinal tree species which occurs widely in tropical Asian regions and has valuable resources for industrial applications. This study aimed to identify paternal parents in an open-pollinated family in a natural forest of A. clypearia, based on the expressed sequence tag derived simple sequence repeats (EST-SSR) markers, to determine which are full-sib seedlings, and therefore provide full-sib families for subsequent studies. 【Method】 The maternal parent ELS31 and 38 fruited candidate paternal parents from a natural population, together with 1 489 open-pollinated seedlings of ELS31, were studied using 15 EST-SSR markers. Seedling diversity and marker polymorphism were estimated. Paternal parents of the seedlings were identified using the method of logarithm of odds, and full-sibs originating from the same maternal and paternal parents were identified. The pollen dispersal range was determined from the distance between the maternal and paternal parents. The diversity of father-derived full-sib families was also examined. A Chi-square test was carried out for the markers to determine whether to follow the Mendelian expectation of segregation ratios. 【Result】 Primer pairs of the 15 EST-SSR markers amplified a total of 89 alleles across the seedling population. The expected heterozygosity (H_e) was 0.525 for the seedling population, indicating the moderate genetic diversity. The polymorphism information content (PIC) estimated with 18 unrelated trees from the natural forest was averaged at 0.736 over the 15 EST-SSRs, suggesting a high level of marker polymorphism. Of the 1 489 open-pollinated sibs, 857 (57.6%) originated from 34 definite paternal parents, with the top ten paternal parents each contributing to 26-184 sib seedlings and other 24 paternal parents contributing to 139 sib seedlings. Selfed sibs were not found, indicating that A. clypearia is an outcrossing species with an extremely low chance of selfing. For the top ten full-sib families, H_o ranged from 0.502 to 0.693, and H_e ranged from 0.417 to 0.544. Higher H_o estimates in these families indicate a certain magnitude of heterozygote excess. The pollen dispersal distance ranged from 10.0 to 559.1 m, with a mean of 119.2 m and the most effective range being within 150 m. A subset of 716 seedlings (83.5%) were generated from the 10 paternal parents within the range of 150 m from the maternal parent. The most distant paternal parents ELS01 (559.1 m) and ELS02 (552.2 m) contributed to 9 and 12 seedlings, respectively. The 15 EST-SSRs distorted more or less from the Mendelian expectation in segregation among part or all of the top ten full-sib families. The mean number of the distorted loci was 8.6 in the top ten full-sib families. The most distorted locus was ARCeSSR141 in the ELS30 fathered family, with a χ² value of 164.55.【Conclusion】 Paternal parents were identified for an open-pollinated family (1 489 seedlings) of A. clypearia using EST-SSR markers, resulting in 10 full-sib families with each comprising more than 20 seedlings. The full-sib families identified here will provide a useful plant material for further studies such as genetic testing, genetic map construction and quantitative trait locus detection.