From the NCBI database, 81,518 Lactuca sativa EST sequences were downloaded, from which 61,757 non-redundant sequences were obtained. In total, 2040 SSR loci were identified, with the frequency of 3.3%. Trinucleotide repeat was dominant, followed by dinucieotide and hexanucleotide repeats. Among 181 types of repeat motifs, （AGA）n and （ATG）n were the dominant repeat motif types, taking up 12.01% and 3.53%, respectively. Totally, four material-special EST-SSR markers were characterized. This study enriches molecular markers of L. sativa, and also lays a theoretical foundation for following germplasm identification, molecular marker assisted breeding and genetic map construction.
