The Sainfoin ( Onobrychis vicifolia) is perennial herbs of the legume family ( Fabaceae ) and is one of the most important forage legumes. Iran is one of the most important centers for genetic diversity of onobrychis. Due to the fact that the sainfoin, as a forage crop, plays an important role in the poroduction of forage in Iran pastures, nevertheless, studies on sainfoin landraces in the country is limit and mainly has been made locally. Assessment of genetic diversity in different sainfoin landraces can keep these plant germplasm resources and contribute to effective correctional programs. Estimate of genetic diversity in the genetic composition of plants and also determines the relationship between species plays an important role in understanding and managing the natural variation within the plant species. The use of molecular markers can help to assessment of genetic variation in different sainfoin landraces. So, in this study, we used SRAP molecular marker as a simple, reliable, entire throughput of genome and targeting of coding secuences. For evaluation of genetic diversity among 17 different masses of onobrychis werw collected from different region of Iran. Genomic DNA was extracted from fresh leaf samples and PCR reaction performed following measurment of quality and quantity of extracted DNA. Out of 10 primer combinations, 88 bands was created, of which 73 (82.95?) were polymorphic. Average amount of PIC = 0.45 represents suitable power of SRAP marker to determine genetic diversity in sainfoin. In the assessment of genetic diversity among masses, the genetic distance among masses was studied between 0.124 and 0.349. In the provincial distribution of masses, the lowest and highest genetic distance was calculated between masses of Russia (P and Q cods) and Damavand and Najaf Abad regions (G and M cods), respectively. Numerical value of 1.33 obtained for gene flow between grouos (Nm) showed that there is gene flow in population but this current can not lead to homogenization of the population. The shanon information index was calculated for primer compositions between 0.31 and 0.52. In The cluster analysis of SRAP data, drawed dendogram with NTSYS-sp, Ver 2.02e could not classify masses in different groups. In other word, commixture of masses in the dendogram showed that there is not any genetic diversityamong species. Principal coordinate analysis (PCoA) of SRAP data showed that sum of first three PCs colud be represented 45.629 ? of the total variation; therfor, the cluster analysis is the best method for evaluation of genetic diversity aong sainfoin landraces. Key Words : SRAP, genetic diversity, sainfoin