ABSTRACT: Random amplified polymorphic DNA (RAPD) was studied to detect genetic markers for three economically important Japanese laminarian species, Laminaria japonica Areschoug, L. religiosa Miyabe and L. ochotensis Miyabe, which were sampled from their representative localities on the coasts from Tsugaru Straits to the Sea of Japan. DNA templates for RAPD were extracted from lamina using a DNA extraction kit and were purified with glassmilk. Reproducible RAPD markers for these three species were detected using three random primers from a total of 15 tested. In L. japonica and L. religiosa, these RAPD markers were confirmed to be useful for populations from other localities. The three species studied showed high intraspecific and interspecific band sharing index (BSI) values. Like annual typical L. religiosa from other localities, biennial individuals identified as putative L. religiosa from Atsuta could be discriminated from L. japonica but not from L. ochotensis by any of the RAPD genetic markers studied so far.