A genetic variation within 29 strains of F. velutipes was analyzed by internal transcribed spacer (ITS) sequence analysis and random amplified polymorphic DNA (RAPD). Seven hundred and twenty base pairs were sequenced during the analysis of the ITS region, but no significant variation was observed among the 29 strains of F. velutipes. Sixteen out of 40 random primers amplified polymorphic RAPD fragment patterns. The polymorphic levels of RAPD bands by some primers 4,3,9,10,20) were very high in all 29 strains, with 3,030 fragments ranging between 200 and 2,000 bp. Intraspecific genetic dissimilarity of the 29 strains was calculated to range from 3.3% to 45% by Nei-Li's method using these 3,030 RAPD bands. The genetic variation among Korean strains was relatively high, with dissimilarities ranging between 17% and 38.6%. In the Neighbor-Joining analysis using the genetic dissimilarities based on RAPD, all 29 strains were classified into 5 clusters. Strains in each cluster showed specific characteristics according to their origin and strains. These results suggested that OPA and OPB primers could be used for developing molecular genetic markers and screening of unidentified (F. velutipes) strains.