Breeding for good quality traits requires selection of parents with a wider genetic diversity. A narrow genetic base in the breeding materials limits genetic gains in breeding. The objective of this study were (i) to analyze Lao traditional and improved varieties for genetic variation using SSR markers and (ii) to determine the genetic diversity of Lao traditional and improved rice cultivars for proper identification and selection of suitable parents for future breeding program. In this study, 61 SSR primers were used to survey the polymorphisms among 251 varieties, of which, two of them were Japanese varieties used as check. Kaslath variety is belonging to Indicatype while Nipponbare is belonging to Japonica-type. Results show that, 50 SSR polymorphic markers detected with a total of 130 alleles identified across 251 cultivars. The number of alleles ranged from 2 to 5 with a mean of 2.76 per locus. Cluster analysis using molecular genetics distances among the 251 varieties generated 3 mean groups, indicating diversity among the Lao varieties. Almost of Lao traditional varieties belong to groups I and group II, while all Lao improved varieties and some traditional varieties belong to group III. Group I consisted of 19 varieties, including Nipponbare, therefore, 18 traditional Lao varieties are belonging to Japonicatype. Group II consisted of 191 varieties including Kasalath, therefore, 190 Lao traditional varieties are belonging to Indica-type. This information shows diversity among Lao traditional rice varieties which are belong to two rice species “Japonica and Idica species”. Interestingly, all Lao improved high yielding varieties (37 varieties) and four traditional rice varieties are belonging to group III, indicating narrow genetic base among these improved high yielding varieties. This is because of almost all improved Lao high yielding varieties bred using IRRI varieties as donors. Therefore, further breeding need to identify new source of genes in order to break limited genetic gain in breeding

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