In this study, we acquired two MtDGAT1 genes (MtDGAT11 and MtDGAT12) from cDNA of Medicago truncatula by using insilico cloning combined with RTPCR. The length of MtDGAT11 is 1 620 bp, encoding 539 amino acids, while the length of MtDGAT12 is 1 524 bp, encoding 507 amino acids. Multiple alignments revealed that both MtDGAT11 and MtDGAT12 shared the typical functional motifs with DGAT1s from other plant species. Expression analysis showed that both MtDGAT11 and MtDGAT12 were expressed in root, stem, leaf, flower and seed, and highly expressed in developing seeds; MtDGAT11 was highly expressed in earlymiddle periods of seed development, while MtDGAT12 was highly expressed in the middle and later periods of seed development. Functional complementation in yeast H1246 confirmed that MtDGAT11 encodes disfunctional DGAT and MtDGAT12 encodes functional DGAT.