Twelve 10 bp random primers were used to amplify DNA samples from 19 original provenances and 5 previously introduced populations of loblolly pine (Pinus taeda L.). It was found that the levels of genetic diversity were very high for both original provenances and previously introduced populations by means of RAPD polymorphic locus rate, which were 81.3% and 99.2% respectively. Eighteen specific bands were detected from 13 of the original provenances. Ten specific bands were lost in 5 of the original provenances. These specific bands and particularly lost bands can be the important basis in the determination of provenance. Based on the distribution frequency of specific bands from original provenances, it was deduced that, although the internal populations were introduced in 3 times, the sources were relatively consistent. They mainly originated from 4 provenances in North Carolina, Florida and Mississippi of USA.