Five thousand and eight hundred publicly available expressed sequence tags (ESTs) of Phytophthora sojae were electronically searched and 415 simple sequence repeats (SSRs) were identified in 369 ESTs. The average den- sity of SSRs was one SSR per 8.9 kb of EST sequence screened. The most frequent repeats were trinucleotide re- peats (50.1%) and the least frequent were tetranucleotide repeats (8.2%). Forty primer pairs were designed and tested on 5 strains of P. sojae. Thirty-three primer pairs had suc- cessful PCR amplifications. Of the 33 functional primer pairs, 28 primer pairs produced characteristic SSR bands of the expected size, and 15 primer pairs (45.5%) detected poly- morphism among 5 tested strains of P. sojae. Based on the polymorphisms detected with 20 EST-SSR markers, the 5 tested strains of P. sojae were clustered into 3 groups. In this study, the SSR markers of P. sojae were developed for the first time. These markers could be useful for identification, genetic variation study, and molecular mapping of P. sojae and its relative species. The average denssity of SSRs was one SSR per 8.9 kb of EST sequence screened The most frequent repeats were trinucleotide repeats (50.1%) and the least frequent were tetranucleotide repeats (8.2%). Forty primer pairs were designed and tested on 5 strains of P. sojae. Thirty-three primer pairs had suc- cessful PCR amplifications. Of the 33 functional primer pairs, 28 primer pairs produced characteristic SSR bands of the expected size, and 15 primer pairs (45.5%) detected poly- morphism among 5 tested strains of. Sojae. Based on the polymorphisms detected with 20 EST-SSR markers, the 5 tested strains of P. sojae were clustered into 3 groups. In this study, the SSR markers of P. sojae were developed for the first time. These markers could be useful for identification, genetic variation study, and molecular mapping of P. sojae and its relative species.