Oryza sativa 'Dahanala' is a traditional red rice variety acknowledged for its thrips resistance. This study focused on the genetic diversity assessment of Dahanala accessions in Sri Lanka. Twenty-six Dahanala accessions conserved at the genebank of the Plant Genetic Resources Centre and six accessions from the Rice Research and Development Institute, Batalagoda, were analyzed using seven seed morphology characters followed by molecular characterization with 31 simple sequence repeat markers, showing a significant genetic variation of the accessions. Accessions 003924/003327 and 0010160/006165 were reported as two potential pairs of duplicates. The polymorphic information content values varied between 0 (RM255) and 0.697 (RM412). Genetic distance ranged within 0.0 and 0.94 revealing considerable genetic variance. Sixteen closely related accessions were selected as a representative set of Dahanala, including accessions 003924, 003327, 006376, 010160, 006165, 006378, 004968, 003304, 006739, 005386, 004507, 003149, 003131, 627, 626 and 629. To assess the variation of trichome phenotypes among Dahanala accessions, leaf trichome density as well as RM277 and RM279 markers, which carry a putative relationship with thrips resistance, were used as morphological and molecular markers, respectively. Results revealed a variation of trichome density from 6.7 to 30.83 trichomes/mm2. According to the molecular marker analysis, both markers revealed polymorphism in thrips-resistant Dahanala accessions and susceptible Oryza sativa ‘Suduru Samba’ accessions, but no clear linkage between the markers and trichome phenotypes within the selected Dahanala accessions could be found. Further studies are needed to dissect the relationship between trichome phenotype and thrips resistance in red rice.