Methionine sulfoxide reductase plays a regulatory role in plant growth and development, especially in scavenging reactive oxygen species by restoration of the oxidation of methionine in protein. A full-length cDNA sequence encoding methionine sulfoxide reductase (MSR) from mulberry, which we designated MMSR, was cloned based on mulberry expressed sequence tags (ESTs). Sequence analysis showed that the MMSR is 810 bp long, encoding 194 amino acids with a predicted molecular weight of 21.6 kDa and an isoelectric point of 6.78. The expression level of the MMSR gene under conditions of drought and salt stresses was quantified by qRT-PCR. The results show that the expression level changed significantly under the stress conditions compared to the normal growth environment. It helps us to get a better understanding of the molecular basis for signal transduction mechanisms underlying the stress response in mulberry.