Random amplified polymorphic DNA (RAPD) markers were used to assess genetic variation within and among Hawaiian populations of an apomictic grass, Heterogopon contortus (pili grass). From among 56 individuals sampled from six populations on O’ahu and Hawai’i, 55 unique genotypes were detected using 33 polymorphic markers. This lack of uniformity among individuals may indicate frequent sexual reproduction in these populations. Analysis of molecular variance (amova) revealed significant variation among populations (30.2%), but higher levels of variation within populations (68.1%). Cluster analysis revealed a high degree of clustering for most populations, but populations from different islands did not cluster together. The presence of among-population differentiation but lack of between-island differentiation may suggest that H. contortus was an early Polynesian introduction to the Hawaiian Islands.